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Dave Parvin
Joined:
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16-Mar-2005
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Started On : 31-Dec-2006 at 09:34:25 PM, #Views : 6004
Topic Subject : Re: Re: Re: How to avoid Dimples in alginate? |
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Ray, I suspect that your second theory about the dimples is the more likely the cause. Plaster that is too thick will definitely cause imperfections. The plaster must be wet or runny enough to thoroughly soak the cotton or cheese cloth or whatever is used to bond the alginate to the mother mold. Any material not soaked might as well be an air pocket which will make an "outie" in the positive. Trying to apply setting up plaster may push in the alginate causing "innies." Once the plaster is too thick to be applied with a paint brush, stop and mix a fresh batch. However, if you disolve some of the first batch into the water for the second, the older plaster will act as a catalyst and cause the new batch to set up even more quickly and you will have added only a few minutes to the process.
According to US Gypsum, the correct plaster to water ratio Impression, Laboratory, or Regular Dental Plasters is 100 parts plaster to 70 parts water by weight. This is the same prefered ratio for Moulding Plaster. I believe you said that you were using 50 parts water which would be too thick.
I don't know why AlgiSlo didn't seem to herp you, I use it all the time with excellent results.
Dave
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