Saki Posted November 29, 2016 Report Share Posted November 29, 2016 I have been using a plaster wedging board made from #1 pottery plaster for about 6 months with no problem. Recently, I started noticing white, fluffy salt deposits on the surface. Some photos are attached. It seems to be worse after I reprocess a batch of clay from slip. (By reprocess, I mean recycle dry clay trimmings by adding water to them, forming a chunky slip, and then scooping the slip onto the plaster, where it dries into plastic clay that is workable for throwing again.) Since this only started happening recently, I suspect it is not "primary" efflorescence from calcium deposits in the plaster board, but rather "secondary" efflorescence from calcium that has dissolved into the water in the slip. From what I understand, the salts are left behind on the surface when the water that has been absorbed by the plaster evaporates into the air. I am using Standard Ceramic 365 English Porcelain for Cone 6. I have been wiping the surface of the plaster clean with a dry brush and shammy, but I am concerned the efflorescence may be damaging the wedging board. I am also concerned that it may have an effect on clay that I re-wedge there. Are these valid concerns? If so, are there any remedial steps I should take to minimize the damage? Thank you. Link to comment Share on other sites More sharing options...
Marcia Selsor Posted November 29, 2016 Report Share Posted November 29, 2016 I think it is salt crystals possibly from the reclaim..or water. I don't think it is harmful.Just wash it off. Marcia Link to comment Share on other sites More sharing options...
Mark C. Posted November 30, 2016 Report Share Posted November 30, 2016 Just wash it off or sweep it off. non issue Link to comment Share on other sites More sharing options...
JohnnyK Posted November 30, 2016 Report Share Posted November 30, 2016 I would scrape It off with a wide blade drywall knife if brushing doesn't get it, then wash off the little residue that's left. JohnnyK Link to comment Share on other sites More sharing options...
Chilly Posted November 30, 2016 Report Share Posted November 30, 2016 For me, this is worse in cool/cold/damp weather than hot. Link to comment Share on other sites More sharing options...
glazenerd Posted November 30, 2016 Report Share Posted November 30, 2016 Simple chemistry: salt/sodium = alkali Vinegar = very mild acid Neutralize salts with mild acid; rinse. Add oil to leftover vinegar = eat salad. Link to comment Share on other sites More sharing options...
Saki Posted December 1, 2016 Author Report Share Posted December 1, 2016 Thanks everyone. I'm relieved to learn this isn't harmful. Chilly, I think that's consistent with my experience, too. I didn't notice this in the summer, only after the weather started to get wet. Nerd, Sounds like a delicious recipe Link to comment Share on other sites More sharing options...
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