How do you remove PU or Silicone type coatings from fabrics?

> Re: How do you remove PU or Silicone type coatings from fabrics?
You don't.
(Which means it is largely not possible.)

Cheers

I've removed urethane coatings from nylon fabrics with dichloromethane, which is available at many hardware stores as a paint stripper. This is a big project, though (even for a small piece of fabric), and it involves using and disposing of noxious and toxic chemicals with flammable vapors.

The dichloromethane usually comes as a gel, and you need to thoroughly rinse the fabric afterward with acetone (or some other organic solvent) to get it off. Disposal of this rinse mixture can be problematic, and you should do some reading about how to do it properly if you plan to attempt this. Do not dump it down the drain, onto the ground, or into a gutter.

Silicone coatings are much more difficult to remove using chemicals. I haven't found anything that works.

I only mention chemical methods because they leave the underlying fabric essentially unscathed (if it is nylon or polyester), unlike mechanical scraping, which abrades the fabric.

poke a bunch of holes in it

I have a stuff sack which had PU coating on it. Over time the PU degraded and turned very sticky making it impossable to close. I soaked it in rubbing alcohol for about a day and that removed most of the PU coating. But that was with degraded PU coating. I don't know if that would work on PU coating in good condition.

Not sure what coating is used in 70's era external frame jansport packs, but I just washed one in a front loader, and the lining was completely decimated!
May have just been do to age?

Your 70's era jansport just had PU coated nylon. I believe silnylon was not available at the time. The only other laminate fabric out there at the time was the very new / very expensive Gortex fabric.

PU does eventually degrade or delaminate . Its happened to me on 2 REI backpacks, one rain jacket, and 2 stuff sacks. All were over 15 years of age or older. I have a couple of itens that are even older that are still in good shape.

I've had this happen, too. PU, in general, is sensitive to hydrolysis and UV radiation. Some urethanes are more hydrolysis-resistant than others, and some have additives that inhibit UV damage, but, as a rule of thumb, PU will eventually be destroyed if it remains wet or gets left in the sun. Silicones are basically unaffected by water and UV radiation.

Thank you everyone for the info and suggestions.