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Celestialexplorer1



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Uv-c to sterilize agar 1
#26643426 - 05/02/20 10:49 AM (3 years, 8 months ago) |
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Ok so I know there are topics in uv-c light for sterilization and a lot of people are against it but I had a thought. Since with agar what you are doing is working with the surface of it, and uv-c is used to sterilize surfaces and found rather inexpensively on Amazon.. well I think you get the idea.
Just wondering what others might think of this idea. Obviously I would still pc the agar and use all sterile techniques but just to go a step further you could make a chamber with the light to hit the surface of the agar to kill any possibly lingering bacteria.
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ninja cat 09
A paranoid android



Registered: 10/11/09
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It's an interesting idea, I think it would be great to sterilize a glove box or workspace in front of a flow hood, but I don't know what it would do to the glove box plastic, plus, I understand that you need eye protection to be around those types of lights.
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Celestialexplorer1



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Well with what I’m thinking it would be more like a glovebox or trunk that is solid in color and non-transparent with a switch on the outside. So you put your agar in (after the cook and pour), close the lid tight so no light can come out and flip the switch and then turn the switch off BEFORE opening to ensure safety. I’ve seen uv-c bar lights on amazon for 30$
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nooneman


Registered: 04/24/09
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It might work if you do it for long enough. The problem with UV is not that it's ineffective, it's that it causes cancer. So like the previous poster said, if you built an enclosed chamber with no light escaping, and let it bake under UV for a couple hours, it couldn't hurt. Just make sure you limit your exposure.
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Celestialexplorer1



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Re: Uv-c to sterilize agar [Re: nooneman]
#26643762 - 05/02/20 01:38 PM (3 years, 8 months ago) |
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Google search revealed up to 8 feet it will make organisms inactive in 30 minutes. So that’s not very long and in a non transparent glovebox and with no peeking it should be safe. Probably do some more research though before deciding to try anything.
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ninja cat 09
A paranoid android



Registered: 10/11/09
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Loc: Mexico
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Quote:
Celestialexplorer1 said: Google search revealed up to 8 feet it will make organisms inactive in 30 minutes. So that’s not very long and in a non transparent glovebox and with no peeking it should be safe. Probably do some more research though before deciding to try anything.
You could make agar by boiling it, not PC the agar and then put plates of it in the UV-C chamber for varying amounts of time to see what happens.
I remember a tech twitter person I follow, who is reputable (@RealSexyCyborg) mentioning that some LEDs that are sold as UV-C aren't actually UV-C, so you'll probably want a way to test them before you buy something off amazon.
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kitten6
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well if your lamp is powerful enough, it can actually turn oxygen in air into ozone which will do a pretty good job of sterilization, it will kill rats as well. Your room will stay completely sterile for a good while. As long as it smells a bit of ozone.
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bodhisatta 
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Re: Uv-c to sterilize agar [Re: kitten6]
#26645318 - 05/03/20 06:41 AM (3 years, 8 months ago) |
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Don't worry about discoloring everything in the room eventually.
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mycorry
The Empirical



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Re: Uv-c to sterilize agar [Re: bodhisatta] 1
#26645806 - 05/03/20 11:48 AM (3 years, 8 months ago) |
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Last time I did research on this I discovered that almost everything in agar(including the antibiotics if you use them) will be damaged or destroyed by the UV-C.
Furthermore, I let a set of plates that I had sterilized with UVC sit in their ziplock bags for a few days, and upon opening them they all smelled like ozone. I don't want a little cloud of ozone hanging out near the surface of my agar ready to murder mycelium.
I can't remember where I got the info on UV-C destroying agar components. 
I have done a lot of testing of UV-C on my own and my best conclusion is that it doesn't really do much for mycology.
*I am trying to add to the discussion. I am not trying to cut anyone's ideas down or be the last word on anything.
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Celestialexplorer1



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Re: Uv-c to sterilize agar [Re: mycorry]
#26645819 - 05/03/20 11:54 AM (3 years, 8 months ago) |
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UV Light Sterilizer E-209 - Ultra Violet Sterilizing Cabinet https://www.amazon.com/dp/B0863HK6VY/ref=cm_sw_r_cp_api_i_YtWREbNBACF9S
Here is basically what I’m talking about ghetto rigging up a solid tub or making a trunk maybe. Depends on if I start doing a lot more agar work.
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AndyHinton


Registered: 12/05/16
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I wouldn't sterilize media with it. You need to cook thoroughly because encased contaminants on the bottom can easily travel up the sides. It's like drinking from a glass with a dirty stem, bad technique.
You can effectively sterilize a working space such as a polypropylene or polyethylene tub. It doesn't reach shadows. So remember to disinfect everything before loading it in the tub, then run the light.
Here's an example of how to use UV light into your setup. The bulb is a 15W Philips Holland fluorescent-type recycled from a flow hood. Invest in a good non-ozone bulb that you can trust emits 280 nm light.
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Edited by AndyHinton (05/03/20 04:54 PM)
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ninja cat 09
A paranoid android



Registered: 10/11/09
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Re: Uv-c to sterilize agar [Re: AndyHinton]
#26647677 - 05/04/20 08:00 AM (3 years, 8 months ago) |
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Quote:
AndyHinton said: I wouldn't sterilize media with it. You need to cook thoroughly because encased contaminants on the bottom can easily travel up the sides. It's like drinking from a glass with a dirty stem, bad technique.
You can effectively sterilize a working space such as a polypropylene or polyethylene tub. It doesn't reach shadows. So remember to disinfect everything before loading it in the tub, then run the light.

If you're disinfecting everything, what's the point? Has it helped reduce your contam rate?
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Celestialexplorer1



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Re: Uv-c to sterilize agar [Re: mycorry]
#26647939 - 05/04/20 10:01 AM (3 years, 8 months ago) |
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That sort of input is exactly what I was looking for mycorry thank you. I didn’t know if it would work that’s why I asked but your point makes a lot of sense and it’s something I had thought about also. It seems like if it kills the bad bacteria it could also genetically alter the stuff you want as well. I’ve heard Uvc can alter human dna.
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Edited by Celestialexplorer1 (05/04/20 10:03 AM)
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leschampignons
Biochemistry + Mycology



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an interesting vid on the subject.
most important of all keep UVC lights away from your eyes and skin. these lights can do permanent damage to you in a short amount of time.
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panne cyanne
albino queen


Registered: 04/15/20
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i take the dimmest view on UV in grows. long term eye damage is possible.
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AndyHinton


Registered: 12/05/16
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Quote:
ninja cat 09 said: If you're disinfecting everything, what's the point? Has it helped reduce your contam rate?
It's all about keeping track of the relative sterility of different overlapping zones, and modifying your workspace and technique to reduce contamination potential.
Say you have a pressure-sterilized petri dish verified by autoclave tape. This encloses a small sterile area for an instance of microbe culture. It's upstream of things already inoculated, themselves upstream wild specimens, etc. To help ensure sterility, you need to disinfect the outside of it and create a reasonably sterile area to handle it in.
That's where the UV light comes in: assuming a clean and disinfected workspace, it will fry and disintegrate any unshadowed DNA in the workspace, killing all exposed contaminants. PP/PET and similar plastics effectively absorb UV spectra, which is why Plexiglass windows turn opaque in the sun. So the rays are well contained in the workspace.
Before I had to assume a 19th-century standard of sterility and adjust my technique to use syringes and ported lids. Now I can assume a mid-century standard and use regular unmodified stuff handled in sterile air. Same low contamination level, almost always traceable to specific mistakes in technique.
An example of technique failure. Some test cryotubes contaminated because I tried to spin down and combine pellets from 25 mL broth in 1.5 mL tubes (bad idea to clumsily manhandle it with toothpicks). Now I'll do what I've always done, but better: pipette 5 mL ice cold saline, shake vigorously, and resuspend those pellets in cryo medium.
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Edited by AndyHinton (05/05/20 10:08 AM)
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panne cyanne
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Re: Uv-c to sterilize agar [Re: AndyHinton]
#26650373 - 05/05/20 10:53 AM (3 years, 8 months ago) |
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unshielded 280nm in an open lab. your far braver than i.
you should read about blue light UV hazards. i was taught anything below 320 nm is risky. PP isnt enough of a shield IMO.
its on the edge of human light perception. that thing is many time brighter than it appears. im not sure id be in the room with that even with UV glasses.
Edited by panne cyanne (05/05/20 11:02 AM)
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bodhisatta 
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I work with UV bulbs that are over 6000 watts and produce ozone I would never consider using UV for at home disinfection of anything.
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brikogen
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Re: Uv-c to sterilize agar [Re: bodhisatta]
#26652839 - 05/06/20 12:11 PM (3 years, 8 months ago) |
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I don't get the hysteria. With everything care and proper education is important. Just like alcohol can set your house on fire if you are not properly informed on how to handle it and its dangers. SAB explosions, PC accidents, Agar bottle explosions...have happened before due to improper use and careless behaviour. If you are not comfortable with using something, don't.
However as pointed out before agar can be sterilized with the proper UV-C light such as the philips bulbs which are made to not generate ozone. Also make sure you cover it with a light blocking container while it's on. It only take a couple of minutes to sterilize agar plates with UV-C opposed to an hour or more to get your autoclave setup ready, reach pressure, autoclave and cool off. Nevermind the huge energy difference.
At Least give people proper instructions so they don't fuck up. Unless someone is asking about gamma radiation sterilization, then you can tell them to back the fuck away.
Edited by brikogen (05/06/20 12:15 PM)
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AndyHinton


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Re: Uv-c to sterilize agar [Re: brikogen]
#26652924 - 05/06/20 01:07 PM (3 years, 8 months ago) |
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For the record, you should only use pressurized steam to sterilize media. Each plate is a sacred garden that you must protect from contamination.
Making a sterile environment is essential. A flow hood is probably the best way. The next best way, I think, is to irradiate an enclosed space.
There's no special instructions beyond wiring a lightbulb, using the thickest PP/PET possible, closing the sash while the bulb is lit, and avoiding ozone bulbs.
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Edited by AndyHinton (05/06/20 01:37 PM)
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panne cyanne
albino queen


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Re: Uv-c to sterilize agar [Re: AndyHinton]
#26653394 - 05/06/20 05:39 PM (3 years, 8 months ago) |
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Quote:
There's no special instructions beyond wiring a lightbulb, using the thickest PP/PET possible, closing the sash while the bulb is lit, and avoiding ozone bulbs.
AND of course, dodging the light itself when in use.
you guys REALLY need to read up on blue light hazards. these things arent a casual lab tool.
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AndyHinton


Registered: 12/05/16
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Anyway, I did some more research. Quality UV-C bulbs are the only ones I recommend because they emit true 254 nm waves. See UV Properties of Plastics: Transmission and Resistance.
This is important because most plastics and glass thicker than 0.5 mm can't pass UV-C spectra. They can only pass high-energy visible light such as UV-A and UV-B, around 300 to 500 nm. Regular window glass is enough to block UV-C. It's necessary to make UV-C bulbs from quartz for this reason.
Some plastics and glass are better than others at absorbing UV waves: acrylics and borosilicate, respectively. Both known for their thickness and vitrified molecular structure. The purer and less homogenized a compound is, the better it will pass UV-C waves. So not a 3 mm thick polypropylene box made in China for mass consumption. You would need something like a dichroic mirror to selectively pass UV-C waves.
When emitted at high power, UV-C catalyzes oxygen to make ozone. That's why bodhisatta's workplace smells bad: 6 kW UV-C spontaneously making ozone. It's also why the late ozone layer was so high up in the atmosphere: UV-C waves were among the first blocked.
The National Weather Service has a good explanation re: calculating the UV index. UV-C is dangerous because it's strongly ionizing, but it's effectively blocked by plastic and glass. The real danger lies in fake bulbs on Amazon that simulate the effect with UV-B and ozone.
Obviously, my bulb emits more than just 254 nm and some of those waves will pass through. So hanging around the light isn't advised, nor is staring at it. Common sense for an uncommon crowd. 
A fun fact: gamma irradiation uses Cobalt-60 to sterilize equipment with the gamma rays the radioactive isotope emits.
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panne cyanne
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Re: Uv-c to sterilize agar [Re: AndyHinton]
#26653774 - 05/06/20 08:06 PM (3 years, 8 months ago) |
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dont mind me. just worked in a light physics lab for over a decade that often did work with biologicals and blue light of various power levels and wavelengths.
if you can see it, and its below 300nm. show extreme caution.
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bodhisatta 
Smurf real estate agent


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 Don't go outside in the sun then.
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AndyHinton


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Re: Uv-c to sterilize agar [Re: bodhisatta]
#26654482 - 05/07/20 06:24 AM (3 years, 8 months ago) |
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Now I'm curious to know the exact UV transmittance of my tub's PP formulation. So I bought a UV radiometer. We'll have a precise answer soon. The meter's spectral response curve is below.
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Edited by AndyHinton (05/07/20 06:41 AM)
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brikogen
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Re: Uv-c to sterilize agar [Re: AndyHinton]
#26655309 - 05/07/20 02:42 PM (3 years, 8 months ago) |
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Quote:
AndyHinton said: Now I'm curious to know the exact UV transmittance of my tub's PP formulation. So I bought a UV radiometer. We'll have a precise answer soon. The meter's spectral response curve is below.

It seems to have little to no sensitivity at the low end of the UV spectrum where the UV-C range is located?
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AndyHinton


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Re: Uv-c to sterilize agar [Re: brikogen]
#26657321 - 05/08/20 12:19 PM (3 years, 8 months ago) |
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Yes. Because we already know about UV-C's poor transmittance through common plastics, and because I only need one such device. UV-C meters with remote probes cost almost $450 new and are difficult to find used.
The question I want to answer is, "What's the relative full-spectrum UV intensity just outside the tub, vs. one foot away from it, vs. ambient sunlight and shade?" That's my intended purpose.
Other answers involving the fractionation of UV spectra are assumed to be fully funded by the inquirer, i.e., buy a Solarmeter 8.0-RP if you want to measure UV-C. I would send you plastic samples to test.
Another quick fact. UV-C lamps are visibly purple for the same reason flammable gases are adulterated with bad-smelling compounds: to indicate the presence of a potential hazard.
See also
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Edited by AndyHinton (05/08/20 11:24 PM)
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panne cyanne
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Re: Uv-c to sterilize agar [Re: AndyHinton]
#26658049 - 05/08/20 06:09 PM (3 years, 8 months ago) |
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Quote:
AndyHinton said: the presence of a potential hazard.
im comfortable with trained professionals in proper labs using these things as needed. i would really hate to see an army of noobs with these things installed in apartments, frat houses, trailers, barns, bedrooms,crawl spaces, and attics.
especially if they realized you can get these things powerful and cheaply.
of course, the whole hobby has its hazards. blue light is pry not the worst of them. but if UV is needed, i would always opt for the most cautious minimum, and absolutely wear UV safety glasses.
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bodhisatta 
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Ok, if y'all want ill try sterilizing agar with UV

These are are 6000 watts. They produce ozone. Even though it's not shown on the graph. There are ozone free variants available for more money but the units are very ventilated just to operate anyway
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panne cyanne
albino queen


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Re: Uv-c to sterilize agar [Re: bodhisatta]
#26658082 - 05/08/20 06:22 PM (3 years, 8 months ago) |
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yowza bod. that would tan an entire sorority in one flash.
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AndyHinton


Registered: 12/05/16
Posts: 434
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Quote:
panne cyanne said: i would really hate to see an army of noobs with these things installed in apartments, frat houses, trailers, barns, bedrooms,crawl spaces, and attics.
Yeah. I think a big danger lies in peeps buying cheap Amazon shit thinking it emits true UV-C waves. They hear that plastic blocks it. But there's a cross point between the bulb's UV emissions and the spectra the plastic will pass. Unique to each setup and with 99.97% not testing it. We'll know next week for a true 15W bulb and about 3 mm thick PP5, at least.
I get a feeling of ominous presence when the light is on, a power to respect. Orange glasses and not being close to it. It's so easy to avoid unnecessary UV exposure. But I've also seen herbs on fitness YouTube irradiating their balls with infrared to "increase testosterone" (and free radicals as by-products of overactive metabolism).
This is all temporary until I can get back to my UV-equipped flow hood. Where the bulb in question is from, an MIT cancer lab. But the radiometer will be useful beyond testing how hot tub is with a ghetto, exposed wires UV bulb taped inside. The new age is here, it's all about the molecules.
PS. You can make a stencil over a plate, spread yeast evenly, and incubate it with UV light overhead to make photo-quality agar art. @yeastograms
Edited by AndyHinton (05/08/20 11:27 PM)
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brikogen
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Re: Uv-c to sterilize agar [Re: bodhisatta]
#26658965 - 05/09/20 01:30 AM (3 years, 8 months ago) |
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Quote:
AndyHinton said:
Quote:
panne cyanne said: i would really hate to see an army of noobs with these things installed in apartments, frat houses, trailers, barns, bedrooms,crawl spaces, and attics.
Yeah. I think a big danger lies in peeps buying cheap Amazon shit thinking it emits true UV-C waves. They hear that plastic blocks it. But there's a cross point between the bulb's UV emissions and the spectra the plastic will pass. Unique to each setup and with 99.97% not testing it. We'll know next week for a true 15W bulb and about 3 mm thick PP5, at least.
I get a feeling of ominous presence when the light is on, a power to respect. Orange glasses and not being close to it. It's so easy to avoid unnecessary UV exposure. But I've also seen herbs on fitness YouTube irradiating their balls with infrared to "increase testosterone" (and free radicals as by-products of overactive metabolism).
This is all temporary until I can get back to my UV-equipped flow hood. Where the bulb in question is from, an MIT cancer lab. But the radiometer will be useful beyond testing how hot tub is with a ghetto, exposed wires UV bulb taped inside. The new age is here, it's all about the molecules.
PS. You can make a stencil over a plate, spread yeast evenly, and incubate it with UV light overhead to make photo-quality agar art. @yeastograms
Why bother with the uncertainty, just cover the box with a towel or light blocking cloth before you switch it on. But I'm more curious though about PP degradation rate when using this. I'm quite happy with my SAB but how fast would it turn it into nacho chips compared to how much you use this.
Also you don't really need a radiometer to check if UV-C is being emitted from your bulb. Just contaminate the shit out of some plates and put them in the chamber. Then set them aside and see what grows on them. If they stay clean then your lamp is good to go.
Quote:
bodhisatta said: Ok, if y'all want ill try sterilizing agar with UV

These are are 6000 watts. They produce ozone. Even though it's not shown on the graph. There are ozone free variants available for more money but the units are very ventilated just to operate anyway

The agar plate that that can sterilize is probably the size of a football field.
Edited by brikogen (05/09/20 02:25 AM)
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bodhisatta 
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Re: Uv-c to sterilize agar [Re: brikogen]
#26659393 - 05/09/20 07:25 AM (3 years, 8 months ago) |
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I actually doubt it will work but..
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AndyHinton


Registered: 12/05/16
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Re: Uv-c to sterilize agar [Re: bodhisatta]
#26659550 - 05/09/20 09:07 AM (3 years, 8 months ago) |
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Yeah. Going by the spectrals, that looks like a yellow and purple light with incidental UV-A emission. But at that power you could probs fry any stray yeasts.
Ideally the bulb would have a peak response close to 254 nm, the smallest amplitude possible, and a bit of visible purple light for safety reasons. The 254 nm target is important because that's peak DNA absorption, meaning the fastest death by DNA scrambling.
This kind of power is really cheap and available, maybe 20€ per bulb. Here are the curves for the Philips TUV T8, and a general reference spectrum. The Sankyo Denki G15T8 currently installed in the flow hood is similar.

If I had to give the technology to a moron and protect them from themselves, it's a hard choice. I really don't know if I'd give them a truly deadly bulb with tight but easily controlled UV-C emissions, or a fake Amazon bulb that vomits UV-B like a tanning salon.
Also, can we please stop talking about UV-C agar sterilization? It can never match the power efficiency of a real autoclave and it's just bad technique.
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Edited by AndyHinton (05/09/20 09:26 AM)
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bodhisatta 
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Re: Uv-c to sterilize agar [Re: AndyHinton]
#26659693 - 05/09/20 10:16 AM (3 years, 8 months ago) |
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Quote:
AndyHinton said: Yeah. Going by the spectrals, that looks like a yellow and purple light with incidental UV-A emission. But at that power you could probs fry any stray yeasts.
Ideally the bulb would have a peak response close to 254 nm, the smallest amplitude possible, and a bit of visible purple light for safety reasons. The 254 nm target is important because that's peak DNA absorption, meaning the fastest death by DNA scrambling.
This kind of power is really cheap and available, maybe 20€ per bulb. Here are the curves for the Philips TUV T8, and a general reference spectrum. The Sankyo Denki G15T8 currently installed in the flow hood is similar.

If I had to give the technology to a moron and protect them from themselves, it's a hard choice. I really don't know if I'd give them a truly deadly bulb with tight but easily controlled UV-C emissions, or a fake Amazon bulb that vomits UV-B like a tanning salon.
Also, can we please stop talking about UV-C agar sterilization? It can never match the power efficiency of a real autoclave and it's just bad technique.
It doesn't peak in the ozone producing territory but it does produce enough ozone that it requires two three phase blowers to cool the bulbs and evacuate the ozone
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bodhisatta 
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Re: Uv-c to sterilize agar [Re: bodhisatta]
#26659698 - 05/09/20 10:18 AM (3 years, 8 months ago) |
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I think the cap will melt or get fucked long before the agar sterilizes. I would use a Pyrex media bottle
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brikogen
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Re: Uv-c to sterilize agar [Re: AndyHinton]
#26659709 - 05/09/20 10:28 AM (3 years, 8 months ago) |
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Quote:
AndyHinton said: Also, can we please stop talking about UV-C agar sterilization? It can never match the power efficiency of a real autoclave and it's just bad technique.
I thought the OP was about sterilizing agar surfaces. I agree that it may encourage bad technique but the idea has some merit. Since UVC sterilization is only a surface treatment it can not replace an autoclave. However it can be used to sterilize agar containers and lids that are not autoclavable, before you pore your sterile agar. Why would you do that? Well perhaps you care about the planet and don't want to add to the pile of plastic waste of the world. Perhaps by using biodegradable containers (paper, PLA, sugarcane...).
But hey what the fuck do I know
Edited by brikogen (05/09/20 10:28 AM)
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AndyHinton


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Re: Uv-c to sterilize agar [Re: brikogen]
#26659725 - 05/09/20 10:37 AM (3 years, 8 months ago) |
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Quote:
bodhisatta said: It doesn't peak in the ozone producing territory but it does produce enough ozone that it requires two three phase blowers to cool the bulbs and evacuate the ozone
That's exactly what I'm trying to avoid: work smarter not harder. This UV-C sterilization is all about peak target emissions from cool bulbs.
My city runs nightly infrared helicopters over my neighborhood. I can't afford to run an Olympic tanning salon just to kill some airborne spores. A knock on the door, a roommate unwittingly invites them in, me with a scientist's tan and a jar of the fuzzy white. I swear officer, it's shaggy mane and oyster truffles. I'm actually expecting crops of both soon, rare flavors indeed. 
Quote:
brikogen said: I thought the OP was about sterilizing agar surfaces. I agree that it may encourage bad technique but the idea has some merit. Since UVC sterilization is only a surface treatment it can not replace an autoclave. However it can be used to sterilize agar containers and lids that are not autoclavable, before you pore your sterile agar. Why would you do that?
It's a bad idea either way. Also, UV-C can't replace gamma rays. Sterile tubes come that way because they're bathed in radioactive decay. My whole setup is optimized for low waste and unsuspicious material flow anyway.
I'm using Mason jelly jars with unmodded PP5 lids, unmodded Ziploc PP5 pints, unmodded mini tubs, and bulk food. Disposables are mostly toothpicks and cotton swabs, and occasional Parafilm backing, pipette tips, and centrifuge tubes. Easy to transport and compost bio waste.
Edited by AndyHinton (05/09/20 10:58 AM)
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AndyHinton


Registered: 12/05/16
Posts: 434
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Re: Uv-c to sterilize agar [Re: AndyHinton]
#26667060 - 05/12/20 04:50 PM (3 years, 8 months ago) |
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Anyway, the extraneous UV waves coming directly off the bulb measured 300 µW/cm2 or basically nothing. This is easily explained by the meter's slight UV-C sensitivity and minor errors in the bulb manufacturing process.
In contrast, daylight measured around 2,000 µW/cm2 when pointed directly at the setting sun. I'll probably buy a Solarmeter 8.0 to measure the life of my bulb and resell this one cheap.
tl;dr: Spend some extra money on a good lamp from a manufacturer that provides spectral curves. If there are no curves then the lamp isn't real. UV-C is a great for sterilizing a dead air box provided you aren't stupid about it. Wear amber glasses and don't irradiate your nuts. Have some respect for this powerful force that only comes naturally from stars.
Edit: Maybe in the long run I should invest in a mass flowmeter and a UV-C radiometer. I'm all about not guessing important facts like the efficacy of my HEPA filter and UV-C bulb. Because this stuff must be regularly replaced. A longtime gripe I've had with FP-style flow hoods not designed for easy filter replacement. Manufacturers may try to enforce this but their assumptions are often absurd, e.g., 1,000 user-configurable "hours" (30 min default) on a UV-C bulb whose lifetime is rated at 7,500 hours. Best to just certify it myself.
Edited by AndyHinton (05/12/20 06:16 PM)
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Celestialexplorer1



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Re: Uv-c to sterilize agar [Re: AndyHinton]
#26668056 - 05/13/20 06:30 AM (3 years, 8 months ago) |
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In the beginning I had labeled this idea only as a further step to pressure cook and sterility technique. It was only meant as a possible extra safeguard against contaminates, obviously this or nothing else could replace good sterile techniques such as a pressure cooker, flow hood, sab, clearing surfaces before work, etc. but I thought of this as a maybe. Just want to make sure that is kept in mind
And for the record I never told anyone to use uv-c to sterilize agar. For the record.
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Edited by Celestialexplorer1 (05/13/20 06:42 AM)
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Celestialexplorer1



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Quote:
Celestialexplorer1 said: Obviously I would still pc the agar and use all sterile techniques but just to go a step further you could make a chamber with the light to hit the surface of the agar to kill any possibly lingering bacteria.
This is my original post... did you read it
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Edited by Celestialexplorer1 (05/13/20 06:45 AM)
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AndyHinton


Registered: 12/05/16
Posts: 434
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Yeah. I just didn't see how it would be different from, "How can I use UV-C to sterilize the space I handle agar in?" Because why would you sterilize something and then sterilize it again in a less effective way? Anyway, I regretted entering the thread after I saw Solipsis's thread.
Some more quick readings. A generic LED bulb in a lamp emitted 400 µW/cm2 of UV. The Carex Day-Light emitted nothing, exactly as advertised.
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Edited by AndyHinton (05/13/20 12:24 PM)
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PinkStormtrooper
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Re: Uv-c to sterilize agar [Re: AndyHinton]
#26668851 - 05/13/20 04:10 PM (3 years, 8 months ago) |
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some light reading about UV-c surface disinfection
http://www.bioline.org.br/pdf?mb08074
-------------------- "say, you got a little astroglide on your moustache"
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PassionateGrower
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Registered: 05/11/20
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FAR-UV...."Seems" to be different and there are several published articles regarding the safety and efficacy. The claims seem high (i.e.) it doesn't penetrate the skin or eyes.
I am no expert on light and just here for the discussion
The Potential for FAR-UV light
Ushio Far UV 222nm safe for human skin
AndyHinton, what are your thoughts?
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Edited by PassionateGrower (05/21/20 08:16 AM)
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AndyHinton


Registered: 12/05/16
Posts: 434
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Hi PassionateGrower,
I wouldn't let that near me without adequate protection (plastic barrier, amber glasses, and unexposed skin) no matter what the claims.
DNA absorption peaks at 254 nm. I personally use a Qubit instead of a spectrophotometer because it's safer, easier, and more accurate. For fluorescence imaging I only use blue LEDs with an amber filter.
Anyway, for sterilization purposes I'd find a UV-C light with a spectral peak as close to 254 nm as possible. That way it ionizes the DNA as fast as possible, zapping contaminants in minutes. A great way to sterilize a working space for tissue culture.
By the way, I sold the broad spectrum UV radiometer and am expecting a UV-C model soon. So I can measure the specific radius of effect around the tub's outside, if any. Just to appease the bogeymanne in the thread. The real use, of course, is to certify my bulb myself. Because the efficacy tends to fade after about 7,500 hours.
Also, UV LEDs typically suck. Unless you're prepared to pay big money for the real thing. Practically my whole existence (house, lab, etc.) is outfitted with LEDs. But not my specialized bulbs. For example, my microscope still uses halogen, but when I retrofit it for fluorescence, I'm definitely using a blue LED array.
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Edited by AndyHinton (05/22/20 03:33 PM)
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panne cyanne
albino queen


Registered: 04/15/20
Posts: 145
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Re: Uv-c to sterilize agar [Re: AndyHinton]
#26688717 - 05/22/20 05:16 PM (3 years, 8 months ago) |
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this thread makes me wanna install the loc-nar in the ceiling of my lab and control it with a key lock switch outside the room.
victory over contams. i would see no issue really if people learned to use them remotely.
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AndyHinton


Registered: 12/05/16
Posts: 434
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Good news! My UV-C radiometer came in. Brand new, factory fresh cert. Calibrated 3 days ago on 2020-05-27.
Any common plastic thicker than cellophane will block most or all UV-C waves. The highest reading I got was 19 µW/cm2 right above the lamp, against the plastic. The intensity decreased by an order of magnitude to 2 µW/cm2 from one foot away. The combination of clear PP5 and amber glasses completely blocked all waves. It was difficult to measure > 1 µW/cm2 from any normal sitting point. But I did reach 7 µW/cm2 around the top perimeter of the tub, right against the plastic.
Some internal readings for comparison. I wrapped my hand in thick cloth, wore long sleeves, donned amber glasses, and took readings inside the irradiated workspace. The intensity around the bottom of the dead air box, where I usually work, ranged from 180–200 µW/cm2 or an order of magnitude higher than any reading outside the tub. Reading the lamp directly maxed out the meter. It only reads up to 2,000 µW/cm2 but I was able to get about 1,950 µW/cm2 a few inches away from the bulb.
The limit when UV-C is considered to be a biohazard: 8 hours of direct continuous exposure to 0.2 μW/cm2 (6 mJ/cm2 total dose). So if I wanted to really damage myself, I would need to expose unprotected mucosa (eyes, mouth, genitals) to the radiation coming off the top of the tub for at least 48 minutes. The damage would basically be a sunburn. I don't even run the bulb for that long because sterilization happens faster than pizza delivery.
The technique works great as long as your bulb is good and you observe some very basic precautions. If done responsibly, it's significantly less dangerous than walking outside on a sunny day. Remember I'm talking about sterilizing a dead air box, not agar. Key takeaways:
- Only buy non-LED bulbs with manufacturer curves/data sheets available
- Use the thickest plastic or glass shield and wear amber glasses when it's lighted
- Assume a non-trivial dose will pass through, but remember it degrades exponentially
- Look at your setup and rearrange it to minimize any exposure to the bare bulb
- You'll probably get a bad sunburn if you work under the lighted bulb
- Even though it's easily blocked, working under UV-C is not a good idea
Anyway, now I can measure my bulb's lifetime and self-certify it. This lets me not use a new bulb in my flow hood every 1,000 hours. One code every 3 years, 7 codes a bulb, 4 bulbs a box. I have infinite free UV-C light and wouldn't have even bothered to find out it if wasn't for Anne Halonium. So thanks for keeping it real.
Quote:
anne halonium said: the age of the urban uber grower, with advanced teks is here. no turning back.
It's possible to build a nice lab bench around UV-C technology instead of, or part of flow hoods. The light is most effective when it's parallel to the the laminar flow. Another reason to consider vertical hoods, besides the disproportionate workspace to filter size ratio. You gotta replace those HEPAs every few years.
Edited by AndyHinton (05/30/20 07:46 PM)
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panne cyanne
albino queen


Registered: 04/15/20
Posts: 145
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Re: Uv-c to sterilize agar [Re: AndyHinton]
#26707764 - 05/30/20 07:07 PM (3 years, 7 months ago) |
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the future does belong to the growers who can exploit new tech tools best. UV is not new, but the spirit for innovation in myco grows is strong.
anne halonium was the harley quinn of mycology arts.
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Tripglass420
Old Head back from hiatus


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Be very careful with uvc as everyone who stated it does damage to eyes I can confirm that through personal experience. I accidentally left one on one night and fell asleep (keep in mind the light was in a closet with the door cracked) and it still emits uv into the air so needless to say I woke up to the worst pain I've ever felt in my life in my eyes and couldn't see at all. My eyes felt like they were filled with sand and I couldn't keep them open for more than one second at a time without tearing up in massive pain. Eye drops actually made the pain ten times worse. Anything I looked at even my phone looked like a star in the sky gleaming so bright I couldn't see a damn thing. I had to lay in bed with a wet rag draped over my eyes for 8hours straight and wasn't back to normal in till the following afternoon. I had only looked at the light for maybe 5minutes total but because it had stayed on for so long it effected the atmosphere of my room just through the door being cracked!
Scariest ducking thing in my life having to wake up thinking I was blind and the pain was a solid 12 on a scale of 1-10. Those things are no joke. They also seem to be bad for mycelium because I had roughly 5 jars all completely stall after trying to use the light on them.
Personal recommendation is that the light is only good for sterilizing the air in your workspace. Using them on anything directly seemed to have negative effects.
Now as far as sterilizing your equipment of maybe using them on empty syringes/jars during storage does seem to help but all in all I think it was just a waste of money. Happy shroomin and good luck!
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bodhisatta 
Smurf real estate agent


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UV is electromagnetic wave. If you're sleeping and your bulb is in a closet you won't fry your eyes.
UV does go in the air yes but it's like a gas that permeates. If your eyes hurt its because you looked at the bulb at some point earlier before bed. The pain takes hours to develop after the exposure. It wasn't the atmosphere in the room lol.
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Tripglass420
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Re: Uv-c to sterilize agar [Re: bodhisatta]
#26749823 - 06/16/20 06:50 PM (3 years, 7 months ago) |
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Well whatever it was it was some serious pain. And your clock must be a little off because the time between looking at the bulb for a few minutes and the pain was less than an hour. Gotta remember that not everyone has the same pain threshold and I'm hypersensitive to eye stuff due to blowing glass for years as well as having blue eyes.
Thanks for the correction though bod you always seem to chime in at just the right time to add in your two cents of passive aggressive loneliness and bahumbuggery haha
And try reading closer next time cause you clearly missed where I mentioned looking at the bulb for about 5min prior to sleeping
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Tripglass420
Old Head back from hiatus


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!maybe I should be careful you don't ban me again for being happier than you

Ps. Bodhisatta is actually spelled bodhisattVa but that's just be chiming in to correct you on something that prolly has some sort of explanation to it but I just wanna seem perfect.....wait I forgot that's your job on here haha
Bottom line is in my opinion uvc lights don't do much good. Thats just my opinion though and everyone is entitled to their own. I'm not gonna spread information that could be harmful to someone just to make myself seem knowledgeable to the forums (prolly the only place you get any sort of positive feelings from others )
Edited by Tripglass420 (06/16/20 06:59 PM)
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bodhisatta 
Smurf real estate agent


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The spelling of my name depends on the language... It's spelled correctly but not in Sanskrit.
All I'm trying to say was the 5 minutes fucked you. Also the mechanism by which the damage takes place and causes pain is well understood
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Celestialexplorer1


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Re: Uv-c to sterilize agar [Re: bodhisatta]
#26819420 - 07/12/20 01:19 PM (3 years, 6 months ago) |
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 For scalpel maybe even agar plates?..
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 To spend just one moment in eternity
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Celestialexplorer1


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Again that’s not an idea for complete sterilization but I make my plates about 50 at a time and refrigerate then take out as I need them so one might be able to take two out and run them through that just to ensure it’s sterile. I don’t know probably pointless actually but it made me think of this thread.
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 To spend just one moment in eternity
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retowen
Forest Dweller
Registered: 08/05/16
Posts: 51
Loc: Canada
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The problem is that many of the uv-c lamps are fake: https://www.reddit.com/r/PandemicPreps/comments/gqgkyf/beware_of_fake_led_uvc_sanitizers_this_simple/
if you find a real inexpensive uv-c lamp please share!
-------------------- Trade List
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