Gretchenmeister said:

Well do you think the caulk in your bathroom has nutes?

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If the mix is non-nutritious, why must you sterilize (pasteurize?) it? Why would bacteria contaminate something with no nutritional value?

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So now I have a reason to sterilize the mix but...

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RogerRabbit said:

Here's my casing and pasteurization tek of choice.
RR

Casing tek

Measure the appropriate amount of dry peat moss for your application. For the first few times you make up casing mix, you’ll just have to take an educated guess as to how much to prepare, then add or subtract from that amount as needed for future projects.

Place the dry peat into a large bowl, five gallon bucket, wheelbarrow, etc., depending on amount. Leave room for the quantity to double, and still allow space to stir. Break up the dry peat very well. There should be no chunks when you get finished, having carefully broken up the peat until it’s all the same consistency. To each cup of peat moss, add one teaspoon of hydrated horticultural lime, and one to two tablespoons of gypsum. Certain species can benefit from two tablespoons or even more of gypsum per cup, so don’t be afraid to experiment, up to ten percent of the amount of peat.

Mix these dry ingredients together well. After mixing, slowly add water to the mix, stirring constantly. Add moisture until field capacity is achieved. I define field capacity as being reached when you can pick up a handful of the mix and no water drips out. If you squeeze lightly a few drops will come out, and if you squeeze very hard, a small rivulet or stream will flow out. Remember, the peat will not absorb all the water at once, so when you reach field capacity, let the mix sit for ten minutes and check again. Chances are, you’ll have to add more moisture.

In a separate bowl, place an equal amount by volume of vermiculite. Fill the bowl with water so the vermiculite begins to float a bit. Turn the bowl over and allow all the water to drain off. A fine mesh strainer works well for larger amounts.

Mix the moistened vermiculite with the moistened peat/lime/gypsum very well and pasteurize at 140F to 160F for one hour. Use as soon as it’s cooled. If you don’t use it all, it’s best to discard or use for your houseplants. Make a fresh batch every time for best results.
RR







Pasteurization tek

Load the pre-moistened to field capacity casing mix, compost or manure into quart mason jars. Place a lid and/or foil over the top. Put the jars into a large covered pot of cold water, with the water filled to 2/3 to ¾ of the way up the jars. A large kettle or pressure cooker works well. If necessary, put a plate or some other weight over the jars to prevent them from floating. Make sure you have a spacer or dishtowel under the jars to prevent the direct heat of the stove burner or flame from cracking your jars. Place the lid on the pot and turn on the stove. Bring the water to a boil, but watch over it and as soon as the water actually reaches a boil, shut off the stove, but leave the pot sitting on the burner. The preceding is for an electric stove that will remain hot for a little while after shutting off power. If you use gas, allow the water to boil for one to two minutes before shutting off the stove. After a couple of hours when they’ve cooled, the jars can be removed and used.

The first time or two you use this technique, monitor the interior of your jars with a meat thermometer. Place it right into the center of the peat or compost. You want to make sure the center of the jar reaches at least 140F and stays there for an hour, but don’t allow it to exceed 170F. Depending on the thickness and capacity of your kettle and lid, you may need to adjust the above times slightly. This tek works because glass is an insulator, so the temperature inside the jars lags the water in the kettle. When I use the above procedure with 7 full quart jars in my All American 921, it comes out perfectly just as written. If you use a smaller pot, you may need to turn the stove on briefly at the ½ hour mark for a few minutes.

The advantage to this tek is there is no pillowcase, etc., to drain and little to no mess or stink is made in your kitchen or pressure cooker. The disadvantage is you have a bunch of jars to wash when you’re done.
RR

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The casing mix provides moisture and (when mixed with a basic pH level) contamination resistance... for the mix itself?

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it sounds like all of this can be achieved with something simple like straight vermiculite.

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. And if the mix can harbor contaminants, it sounds to me like you're just adding another dangerous factor.

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Again, why not just break up a cake and allow it to grow in a pan in a FC?

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