Slowing plaster drying time

[loathar]

I know this has been asked many times, but I can't remember what your supposed to add.(duh?) I guess those brain cells abandond ship.

[jeffrey-wimberly]

Two teaspoons of common vineger added to each pint of water will serve as a retarder.

[Anonymous]

Try about 1 teaspoon full of vinger, always worked for me smells alittle funky.

[loathar]

VINAGER! That's it! THANKS!

[1train1]

 

 I remember reading about the temperature of the water (hot or cold) acting as a 'speed of drying' factor. I don't remember which one slows or which one quickens the drying.

 Unfortunately being at work - I don't have the article in front of me.

[modelmaker51]

 

 I remember reading about the temperature of the water (hot or cold) acting as a 'speed of drying' factor. I don't remember which one slows or which one quickens the drying.

 Unfortunately being at work - I don't have the article in front of me.

 

Hot speeds it up, cold slows it down. Hard to control, though, vinegar works great, just experiment with the mix.

[tatans]

Try glycerine from your drugstore, it slows down the evaporation of the water in water color paint. It works like a charm, you will have to experiment a little bit. It should work on plaster.

[ARTHILL]

Just a note: plaster does not dry, it cures.

[jfugate]

Also baking powder will retard plaster set up. Add about half a teaspoon to a cup of dry plaster and mix it in well to slow the setup time by about 3 times.

The nice thing about baking powder is you can premix it with the plaster. I empty out the 25 lb plaster of paris bag into two big buckets with lids. One is marked FAST PLASTER and is straight plaster of paris. The other is marked SLOW PLASTER and has the baking powder thoroughly mixed in already (about 1/4 cup).

For each given project, I just use the plaster I want. If I want something that sets up somewhere between the fast and slow plaster, I just mix the FAST and SLOW plaster 50-50.

It used to be you could get dry Patching Plaster in bags, but that's getting rare these days. Patching Plaster sets up much slower than plaster of paris, and the extra working time can come in handy.