Beer for My Plaster pg 4
I'd rather have a fulll bottle in front of me than a full frontal labotomy.
BEER, finally something I can relate to!
The old timers were tricky old buggers. They wouldn't tell you a whole lot. They knew stuff but it wasn't easy to pick their brains. Unless you were vigilant they would take those secrets to the grave.
Some old-time tricks to change the setting speed of plaster:
To slow down the set of plaster, the old boys would add some ammonia or stale beer to the water. In the early history of the plaster business there was plenty of beer to go around in the shops. Owners provided a pint of beer for lunch or allowed the men to bring their own. Boy, the second half of the day always seemed so much better in those days!
Old-timers would add a little alum to their water to speed up the setting of their batch. Alum will also make the casts harder.
These secrets are handed down from generation to generation and no specific directions are given. Furthermore, each type of plaster requires different formulas. Experimenting is the only way to discover what effects these additives have. You have to experiment to see how this will work for you. When starting out, it's best to just use plain plaster.
Setting Additives; Another way to modify your plaster mix is to use comercial additives.
Like any medicine taken to produce a cure, these additives may have side effects; most common is a weakening of the plaster.
A better way to control the setting time of your plaster is to vary the temperature of the water. Cold water slows the set. Hot water speeds the set. Also you need to control the amount of water you use in your mix. As described below.
The next info is the heart of being able to control the hardness and setting time of your mix. Study it well.
For specialized purposes, you may have to gauge your plaster.
The Gauging of Plaster
This is an old-time term, but the process is still the same. It is not to be confused with a type of plaster called Gauging Plaster. The gauging of plaster refers to a method of determining whether you will have a hard or soft plaster cast.
Setting Additives
Another way to modify your plaster mix is to use comercial additives.
These secrets are handed down from generation to generation and no specific directions are given. Furthermore, each type of plaster requires different formulas. Experimenting is the only way to discover what effects these additives have. You have to experiment to see how this will work for you. When starting out, it's best to just use plain plaster.
When you are sifting your plaster into the water, you will notice that it will begin to settle just below the surface. If you wait a minute, you will see clear water above the plaster. That amount of clear water is your gauge. You can leave 1/4" to 1" of clear water over the plaster to make a weak plaster mix, or you can bring the plaster exactly up to the surface level for a thicker mix and harder casting. For a super hard mix, pile up the plaster in high islands and let them become thoroughly damp before mixing.
Remember we are talking about a Beta Hemi Hydrate plaster here. Beta for short.If you want to impress your friends learn the terms Beta and Alpha plaster.
How to gauge your mix. This would be a soft mix. With one inch of water over the plaster this plaster would be weak. It would provide a very soft cast for carving.
This batch has a few islands rising up 1/4" to1/2" above the water level. This would be a normal mix. It would be strong enough for general mold and casting work. It would be easy enough to carve yet strong enough not to break easily.
The plaster in this batch has islands rising 1 inch to 2 inches above the water level, which isn't even visible any more. A casting made with such a batch would be very hard. Some sculptors like a mix like this because it carves more smoothly.
Depending on how long you have taken to get the plaster into the water and how much you have piled above the surface level of the water.(one minute should do for a small batch), let the mix slake (soak) for one to two minutes before mixing.
Mixing your batch of plaster
You can use your hand or you can use an electric drill with a mixer attachment. If you use your hand you may want to wear rubber gloves. I don't and I haven't for 40 years. One of my hands fell off a while back but I make do. ( Seriously? I think you know me by now.) Plaster will dry your skin somewhat. Hand lotion will help keep them in good shape. At times my hands become so extremely dry and cracked its painful just to pick things up. I find Jergens Ultra Healing Cream works.
When you use your hand to mix, you can feel every lump and judge the smoothness of the mix. Batches over 2 gallons are not practical to mix with your hand. A Hanson mixer blade attached to a 3/8" or 1/2" electric drill will be needed for larger batches. Very small batches can be mixed with a cake spatula. (Up to about 2 pints.)
The way to use the hand method is: place your hand flat down in the bottom of the bucket, spread your fingers wide, and shake your hand back and forth to agitate the plaster on the bottom. Every once in awhile, use your hand to move some plaster from other areas to the bottom and continue shaking your hand back and forth. Do not take your hand out of the bucket during the entire mixing process. That would introduce air into the mix. You will notice that the plaster creams after a certain point. It takes on a definite change in texture. See if you can detect when it makes the change. It will have more body, feel smoother and creamier. You must mix beyond this stage for the plaster to set properly. Keep mixing for three minutes. Yup, three minutes buckaroo. Seems like a long time, but that's what it takes to make a creamy, smooth mix. Alpha plasters get mixed for 6 minutes.
You can mix longer than that, and you will have a harder, stronger casting. Be careful not to mix so long that your plaster sets up in the bucket. It's a game of chance once you go beyond three minutes. How long can you go? Mixes that you have guaged with 1/4" of water on top can be mixed longer. Ones that you have piled up islands on the surface are more likely to set up before you pour all of the plaster out of the bucket.
So set your egg timer - ready...set...go! Have fun.
Get plastered responsibly.
Remember the rule I before E except in Budweiser!
Dan Kijak Plaster Master phone 610 -391- 9277
e-mail dan@plastermaster.com
