SFD Punch Tek(tomcards)I recently discovered a great tool for creating a 1” synthetic filter disc (SFD) that I use RTV to adhere to my drilled quart jar lid. Inspiration for this tek came from D3monic's brilliant
Perfect Transfers and Agar Tek, which employs a punch to excise a plug of agar from a plate. I bought a set of leather punches. The punch is the only way to go.
The tried and true tek for creating a 1” SFD involves placing a quarter on a SFD and tracing it with a pencil. You then cut the traced disc from the SFD. You can trace and cut eight 1” discs from a 90mm SFD. The tracing is easy. But cutting out the discs is a time-consuming, painstaking, tedious process.
A 1” SFD can be created much more efficiently and effectively using one terrific tool.
REQUIREMENTSGeneral Tools 1” arch punch.
Hammer.
Punch Pad or cutting board.
Steel or concrete foundation.
90mm SFD
Behold the General Tools 1” arch punch. It’s available at Amazon for $15.95.
You’ll use it to quickly punch out perfect 1” SFDs.
Find a flat, dense, heavy surface, like a sidewalk, slab of concrete, or a piece of steel. It must be on the ground floor. You want a solid, impenetrable foundation that won’t absorb and lessen the force of the hammer strikes.
Find a cutting board or a piece of dense wood, plastic or composite material to serve as a punch pad. You want a dense punch pad with just a bit of “give” that will absorb some of the impact. Avoid metal, stone and concrete cutting boards because they don’t “give”. The punch’s cutting head will punch through the SFD and slam into the impenetrable surface, dulling the cutting head. Don’t do it.
You’ll have to experiment with cutting boards or plastic or other materials that you have on hand to see what works best for you. I initially used a wooden cutting board. It worked pretty well, but was a bit too soft. It had a little too much “give”, requiring additional hammer blows to cut the SFD. The punching left numerous circular indentations in the cutting board. My wife isn’t pleased.
The leather punch set that I mentioned above included what looks like a small mouse pad. It’s the best punch pad I’ve located so far.
It’s a version of what’s called a, duh, Punch Pad. This punch pad is available at
https://districtleathersupply.com/products/punch-pad.

It comes in different sizes. When I wear out the pad I’m using, I’m going to order the 6” x 8” pad that costs $12.00. I encourage you to shop around for other brands.
Place your punch pad on top of an impenetrable surface. I use the concrete base of my fireplace.

Put a 90mm SFD on top of the punch pad.
Place the cutting head of the punch level onto the SFD as close to the edge as possible. This positioning allows you to punch the maximum number of plugs from the SFD.
Pick up a handy hammer and strike the punch hard, two or three times.
Slowly raise the punch. You’ll find an SFD plug stuck into the cutting head. Success!
When you punch your very first SFD, you may lift the punch and see that the plug hasn’t been completed severed from the SFD. Part of the plug may still be attached to the SFD. This means that you didn’t have the cutting head level on the SFD, and the striking force wasn’t evenly distributed on the SFD.
No problem.
Lower the punch to its original position on the SFD, lining up it up precisely with the already cut portion. Tilt the punch ever so slightly toward the attached section of the plug. This intentionally un-level placement will focus the force of the next hammer strike to the attached section.
Using a bit less force, whack the punch again with the hammer.
Raise the punch and the plug will be stuck into the cutting head.
Place the blunt end of a pen into the arch of the punch, behind the plug, and gently push the plug out of the punch.
There may be a few tiny strands of filter attached to the otherwise perfectly circular plug. If you’re compulsive, snip them off with a small pair of scissors.

SFD Slant CapTo make agar slants, I use 20mm x 100mm test tubes with screw caps. If you too use test tubes, read on.
The tried and true tek for preparing a slant is to pour agar into a test tube with a hydrated wooden stick in it. Then you screw on the cap, unscrew it about ¼ turn, cover the cap with foil and PC the test tube. When the test tube comes out of the PC, you tighten the cap and let the agar solidify.
Then you put a plug of colonized agar into the slant and screw on the cap. You unscrew the cap ¼ turn and seal the cap/tube juncture with Parafilm.
As I was preparing to order the 1” punch, an idea emerged. We use SFDs on the lids of quart jars, pint jars and half pint jars. Smaller and smaller containers. Why not proceed in that diminishing direction and create mini SFDs for slant caps?
I researched the idea and couldn’t find any previous citations. So this may be the first time that this tek has appeared in print. If so, I’m pleased as punch!
REQUIREMENTS
General Tools 5/8” arch punch.
Hammer.
Drill.
Drill bits.
Vise Grips.
Empty, assembled cardboard box.
Punch Pad or cutting board.
Steel or concrete foundation.
20mm test tube screw caps.
90mm SFD.
Aluminum foil.
Needle or pointy tool.
OPTIONAL MATERIALS
Acetone.
Q-Tips.
CAPS
My test tube cap has a rubbery gasket glued to the inner top of the cap. Many brands of test tube caps have a gasket made of this type of material. Some gaskets are made of what appears to be thick, coated card stock.
And some caps have no gaskets.
If your cap doesn’t have a gasket you can skip this section and proceed to Drilling.
On my first attempt, I left the gasket in place and drilled through it and the cap. I discovered that the hole in the gasket was smaller than the hole in the cap. The damn rubber contracted, creating a smaller hole. The small hole in the gasket would impede gas exchange. The gasket had to go.

Because the hole in the cap was larger than the hole in the gasket, the gasket was visible through the hole on the top of the cap. I inserted the blunt end of a small drill bit through the cap hole, pushed out the gasket and discarded it.
I have only used this tek with rubbery gaskets. I don’t know if gaskets made of other material suffer the same “shrinking hole” phenomenon, but I doubt it.
Regardless, I recommend removing the gasket from the cap before drilling. I want my mini SFD snug against the top of the cap, with nothing between them.
Some gaskets are heavily glued to the cap, making them difficult to remove. Some gaskets aren’t glued at all. I’ve unscrewed caps from brand new test tubes and the gasket fell out of the cap, or the gasket was resting on the mouth of the test tube.
To remove the gasket, stick the point of a needle or some pointy tool between the gasket and the inner wall of the cap and pry out the gasket.
If the gasket won’t budge, it’s securely glued to the cap. You need to break out the acetone. Pour acetone into the cap until a thin layer covers the gasket. Then stick the needle between the gasket and the inner wall of the cap and dig around and pry out the gasket.
There may be some adhesive stuck to the inner top of the cap. I don’t think the adhesive is harmful. If it was, they wouldn’t use it in test tubes that typically contain biological, often human, material. The mini SFD is going to cover it anyway. But if you want to err on the side of caution, use a Q-Tip and acetone to remove it.
Once the gasket is removed, you can begin…
DRILLING
To avoid cracking the cap or creating plastic burrs on the inside of the cap which are nearly impossible to remove, always drill from the inside of the cap.
Place the cap, mouth-upward, onto the cardboard box. The box provides a stable base for the top of the cap while drilling.
Leaving the cap on the box, lay the open Vise Grip on the box and gently clamp it around the cap. Use the least amount of pressure necessary to securely hold the cap. Don’t squeeze or deform the cap. Too much pressure can cause the cap to crack while drilling.
The reason that you leave the cap on the box while attaching the Vise Grip is that you want the cap to remain flush with the box for even support while drilling.

To reduce stress on the cap and prevent cracking, drill progressively larger holes until you reach the desired diameter.
With one hand, hold the Vise Grips steady on the box.
Use a 1/16” bit to drill a hole through the cap and the box.
Use a 1/8” bit to re-drill and expand the hole.
Finally, use a 3/16” bit to enlarge the hole to the desired diameter.
I initially drilled a ¼” hole, but it just looked too big relative to the cap. I feared that removing that much material might comprise the integrity of the cap after repeated PCing.
I also worried that a ¼” hole might allow for too much gas exchange, causing the agar to dry out too quickly.
With the traditional, unscrewed cap tek, the gases slowly, circuitously flow around the narrow threads of the tube until they exchange with ambient gases. Translating the combined size of that tight exchange pathway to hole diameter is beyond me. But visually and intuitively, a 3/16” hole just
feels right.
Having a hole in the cap permits direct, linear gas exchange with the environment, rather than the tight, circuitous route the gases must take through the threads of an unmodified, unscrewed cap.
PUNCHING
Buy a General Tools 5/8” arch punch from Amazon. They cost $14.25.

In the manner previously described, place your punch pad on an impenetrable foundation.
Place a 90mm SFD on top of the punch pad.
Punch out many mini SFDs!

Place the drilled cap mouth-upward on a flat surface.
Insert the mini SFD into the cap and push it flush using the end of a pen.
Screw the cap onto the test tube. You’re done.
There’s no need to adhere the mini SFD to the cap. The diameter of the mini is greater than the diameter of the test tube’s mouth. It won’t fall into the tube. The mini is also locked securely in place between the tube and the cap.

Put a hydrated wooden coffee stirrer in the test tube and add your agar.
Screw the cap on tightly for the first time in your life!
Wrap aluminum around the cap.
Place the slant into the PC and sterilize as usual. If you put your slants in a jar, as I do, there’s no need to put a lid on the jar.
Remove the sterilized slants from the PC and remove the aluminum foil from the caps.
Place the slants on an inclined surface and let them cool.
Storing SFD SlantsIf you plan to store the slants for a while before you inoculate them, the caps must be covered to decrease evaporation. You’ll need:
Ziplock freezer bag, or any thick, polyethylene bag.
1” punch.
Punch pad.
Tape.
Place the punch pad on an impenetrable surface.
Place the freezer bag on top of the punch pad.
Position the punch on the bag. You’re going to punch through both layers of the bag, creating two discs. Hold the bag in place with your free hand to ensure that the two layers don’t slide apart while punching.
Strike the punch with one moderately hard blow from the hammer.
Lift the punch, remove the two discs and repeat as needed. You’ll get dozens of discs from one bag.

Tear off two 2.5” pieces of tape.
Stick a piece of tape to the center of the disc, ensuring that equal portions of the tape extend beyond the edges of the disc.
Center the disc on top of the SFD cap and press it against the cap with your finger.
Pull downward slightly on one end of the tape to apply pressure and then stick the tape to the cap. Repeat with the other end of the tape.
Place the other piece of tape perpendicularly across the first piece of tape, apply pressure and stick its ends to the cap.

To inoculate the slant, peel off the tape/disc and put the slant in your SAB or in front of a flow hood. Remove the cap, insert your puck of colonized agar and screw the cap on tightly.
Remove the slant from the SAB, put it in your grow area and watch it colonize.
Replacing Regular Caps With SFD CapsI had four prepared slants with regular caps. Since I now have SFD caps, I wondered what to do with those slants. I certainly wasn't going to use the standard “unscrew the caps and seal with Parafilm” procedure. That would be a pointless step backward. And it seems wasteful to dig the agar and coffee stirrer out of the test tubes, clean the tubes and use them later.
So I developed a simple tek to replace regular caps on existing slants with SFD caps.
REQUIREMENTS Quart jar with SFD lid.
Pint jar.
Aluminum foil.
Scissors
SFD caps.
SAB or Flow Hood
Cut four 4” x 4” squares of aluminum foil.
Place one SFD cap mouth-down in the center of the foil.

Fold the far edge of the foil toward you, over the top of the cap.
Fold the near edge of the foil away from you, over the top of the cap.
Fold the left edge of the foil to the right, over the cap.
Fold the right edge of the foil to the left, over the cap.
Press the seams together.

Wrap the other caps in the same manner.
When you eventually unwrap the cap it will be safely mouth-down on the foil.
Put the wrapped caps in the quart jar
mouth-up. If you put the caps in the jar, mouth-down, the SFD may fall onto the aluminum foil, due to contraction while PCing.
Cover the lid with foil.
Put the jar in the PC and cook it at 15 psi for 25 minutes.
Remove the jar from the PC.
Remove the foil and let the jar and caps cool.
Wipe the pint jar with 70% alcohol.
Wipe the prepared slants with alcohol and place them in the pint jar.
Place the pint jar inside the SAB on the left side.
With the quart jar in your left hand, place the jar inside the SAB and hold it in the air. Don’t set it down.
Place your right hand inside the SAB and unscrew the lid. Place the lid on the floor of the SAB, off to the right and out of the way.
Gently pour the caps into your right hand.
Place the jar on the floor of the SAB, off to the right, near the lid.
Place the wrapped caps on the floor of the SAB, a few inches apart, with the caps
mouth-down.
Unwrap the first cap, leaving it mouth-down on the foil.
With your left hand, remove one of the slants from the pint jar.
Rotate the slant between your left fingers, turning it upside-down with the cap pointing toward the floor.
With your right hand, unscrew the cap from the slant and slowly put the cap on the floor off to the right near the other debris.
After you remove the cap from the slant, DO NOT move your left arm or left hand. Hold the slant as still as possible. Rest your forearm on the bottom edge of the SAB arm hole if you need to.
With your palm-down right hand, using only your thumb and second finger, pick up the cap, keeping it mouth-down.
Slowly move your right hand to the left, until you’re holding the cap directly under, and a few inches below, the mouth of the slant.
Extend your right index over the top of the cap until the pad of your finger contacts the far side of the cap.

Draw your index finger toward you, which will cause the cap to turn mouth-up.


Immediately raise the cap to the mouth of the slant and screw it on.
Turn the slant upright and place it in the pint jar.
Repeat the procedure with the remaining slants and caps, always unwrapping one cap at a time.
Remove the cup of slants from the SAB.
Place the slants in the grow area.
I put the SFD caps on the slants on 12/12/20.

I watched them for three days for signs of contamination.
12/13/20: The slants chill.

On the left are my existing slants that I re-capped with SFDs. I continue to obsessively monitor them for contamination.
On the right are the newly poured, SFD-equipped slants. The evaporation near the top of the test tubes confirms effective gas exchange.
Behind them is a fully functioning miniature electric chair and a pair of old school defibrillator paddles that can still start or stop a heart.
12/15/20: Three days after re-capping existing slants with SFD caps and creating new SFD slants, here are the photos. The slants formed a bit of condensation after I moved them from my sweltering 78 degree "mush-room" to the 70 degree kitchen to take these photos.

The re-capped slants. Gas exchange and no signs of contamination!

The newly created SFD slants. Gas exchange and no contamination!
Success!
12/24/20: To decrease the risk of contamination while transferring a plug of mycelium from a plate to the SFD slant, I didn't want to set the cap or slant on any surface. I also needed to ensure that the cap would remain mouth-down and the slant would remain horizontal.
So I developed a grip aptly called
SFD Slant Grip Let's assume you've already punched a plug on the plate and replaced the lid, but you haven't removed the plug yet. Use this procedure to get into the grip.
Inside the SAB, pick up the slant from wherever it has been reposing and position it in your palm-down left hand so that ONLY your curled left index finger grips the horizontal slant about 1" from its bottom.
Spread apart your left hand's middle and ring fingers.
Hold the slant horizontally, several inches above the plate from which you're going to remove the plug.
With your right hand, unscrew the SFD cap from the slant and turn the cap mouth-down.
Jam the mouth-down into the fork between your left hand's middle and ring fingers. Your left middle finger and thumb are now available for duty.

With your right hand, pick up the scalpel.
Lower your left hand and use your left middle finger and thumb to grasp the lid.

Raise your left hand, removing the lid while maintaining its horizontal orientation.
With your right hand, use the scalpel to remove the punched plug.
Immediately lower your left hand, putting the lid back on the plate.
Raise your left hand above and away from the plate.
With your right hand, carefully insert the scalpel into the slant and deposit the plug on the agar. Avoid touching the mouth of the slant with the scalpel.
Place the scalpel wherever you place it when you're done with it.
With your right hand, carefully remove the cap, keeping it mouth-down, from between your middle and ring fingers.
Move the cap to the mouth of the slant and screw on the cap.
Today, on Christmas Eve, using the tek described above, I transferred a plug of Rustywhyte from my master plate to the premiere SFD slant. Let's hope that Santa brings the gift of growth.
12/26/20: We have happy mycelium!!!


So far, so good. The tek appears to be successful.
12/29/20: Rustywhyte growing well after five days in the SFD slant.

I hope this update and the photos inspire you to try SFD slants.
I welcome all input.
Thanks,
Tom