Well that answers my question!
Not to beat a dead horse, but I asked ChapGPT AI why vermiculite insulation in the large 3 cubic bags is no longer sold in the stores. Here is the response I received.
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Vermiculite insulation, once commonly available in large 3-cubic-foot bags, has become harder to find for several reasons:
### 1. **Health Concerns Related to Asbestos**
One of the primary reasons for the decline in the availability of vermiculite insulation is the association with asbestos contamination in older vermiculite products. For many years, vermiculite was mined from a site in Libby, Montana, which was contaminated with asbestos, a dangerous material that can cause serious health problems such as lung cancer, mesothelioma, and asbestosis when inhaled.
Although vermiculite itself is not hazardous, the contamination with asbestos has made consumers and companies wary of using and selling it, even though modern vermiculite is generally considered safe. However, this historical link has led to a reduction in demand and caution in the market.
### 2. **Shift to Alternative Materials**
Due to concerns about asbestos and a desire for safer alternatives, many consumers and businesses have shifted toward other insulation materials. Products like fiberglass, cellulose, and spray foam insulation are now more widely available and popular. These alternatives offer better insulation performance and don't carry the same health risks historically associated with vermiculite.
### 3. **Limited Demand for Large Bags**
Large 3-cubic-foot bags of vermiculite were once popular for both insulation and gardening, but with the decline in use for insulation, the market for such large quantities has shrunk. Vermiculite is still used in gardening and horticulture (to aerate soil and retain moisture), but it's typically sold in smaller bags for these purposes, as gardeners don’t usually need large quantities.
### 4. **Market Availability and Supply Issues**
There may also be issues related to supply chain disruptions or availability from manufacturers. Vermiculite, being a mined material, could be subject to fluctuating production levels or regional shortages, especially if demand for it is lower.
### 5. **Regulations and Safety Standards**
In some areas, the sale of vermiculite insulation may be subject to more stringent regulations due to the potential asbestos risk. This could affect its availability in certain regions or stores.
### Alternatives
If you're looking for vermiculite specifically for gardening, you can still find smaller bags in home improvement or garden centers. If you're looking for an insulation solution, modern alternatives such as cellulose, fiberglass, or spray foam are safer and more widely available.
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Well that explains things better to me. However, I especially took note of
"If you're looking for vermiculite specifically for gardening, you can still find smaller bags in home improvement or garden centers."

That's true, you can buy the small bags, but at 4X the cost!
I still have a partial bag of vermiculite insulation for mixing into potting soil. I think I will start mixing in some shredded paper or shredded cardboard (10-20%) to make the vermiculite last longer. I don't plan on buying those small "garden" 8 quart bags of vermiculite due to the high cost.

I have all the chicken run compost in the world for my outside gardens. However, that compost is full of life (bugs, worms, etc...) and has proven not to be good inside the house when the bugs hatched. That soil life is what makes it so good in the raised beds. But I don't know if I sterilize the compost (hot water or baking) for indoor pots if that would just ruin all the benefits of my compost. Unless someone knows better, I think I need a sterile medium for my indoor pots and have to feed fertilizer for the plants.