[Cob] Alum and Soap over horizontal Lime Plaster surfaces?

[Quinn]

Given that you'd mixed the soap with acrylic, I think its safe to say that the acrylic is what's containing it.  Liquid dish soap is detergent in any case, not really soap, though I don't know if that's what people use when they mean soap.

Unless the soap and alum combo polymerizes somehow, and it's possible -I'm not a chemist, I still don't understand how it would work.  I see where Bill Steen mentions it, but no specifics are mentioned.  I'd need to experiment or have someone give me a deeper explanation.  Anyone?

As for the bench, no I would hope no one would be taking a bite out of it!  But if they plan to sit on it with shorts on for any length of time it might not be a good idea-- although as Amanda pointed out, it is used in fabric dying (traditional) so it couldn't be too bad for the skin.

If you use it, let us know if anyone gets rashes and then we'll know!

Quinn

> 
> > Wouldn't the soap just... re-suds up and wash away? 
> 
> 
> Uh, no, I don't think so.  I use regular ol' liquid dish soap in my 
> acrylic water based paints (to extend drying time) and none of it 
> has ever "re-suds up".  
> 
> > Ingestion of 30 grams (1 ounce) has killed adults. Huh. And you 
> find it right next to the allspice.  
> 
> Well, I would hope no one would take a bite out of my cob bench - 
> lol!  But the point about folks being sensitive to alum (eyes skin, 
> etc.) would likely be a problem on a bench where skin would come in 
> contact with it....
> 
> BUT I was reading earlier today about a patent that was obtained by 
> a fella back as early as 1876 (for a mixture that included alum that 
> was put on canvas tents and uniforms to waterproof and prevent mildew 
> & mold) and there were reports even way back then that the fabric 
> treated with this stuff did irritate the hands/skin of some soldiers...
> however, the pertinent point was that the fabric didn't irritate anyone 
> until they went to cut the fabric when mending, etc.  So, perhaps the 
> alum/soap mixture on a cob bench would NOT irritate anybody as long as 
> it was properly maintained and not allowed to dry/crack/flake, etc.  
> 
> Kathy