View single post by Tod
 Posted: Sat Jul 15th, 2017 02:28 am
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Joined: Tue Oct 24th, 2006
Location: Monson, Massachusetts USA
Posts: 246

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I've been "chatting" online with someone who makes his own cement. When I told him my basic recipe (boiled & raw linseed oil, whiting and color to suit, occasionally a splash of turps to help mixing as it seems to evaporate quickly) and said that I felt cement is best when it remains elastic rather than becomes rock hard.

He likes a similar mix but insists on adding plaster of Paris because it makes the cement "stronger". He also maintains that the lack of plaster will result in whiting drying out & becoming white powder. While I've seen this sort of powder in some old leads, I never thought it might be dried out, oil-less whiting.

He also contends that if plaster attracts humidity from the air then his open bag of plaster should be hard as a rock!

I thought the oil & whiting created some sort of chemical reaction which bonded the whiting and the curing oil. I also thought plaster needed water to set up and assumed oil wouldn't make it hard.

I feel fine about folks having their favorite recipes but I'm not chemically knowledgeable enough to be sure others who read our "chat" will get the best information or even the best foundation for forming an opinion. Can anyone here clear up at least the chemistry for me? I doubt that this person will change his mind but I'm very uneasy about leaving the science in doubt.
Thanks, Tod

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