July 20, 2009 @ 2:25 pm
Does wet plaster stick to already dry plaster after the wet plaster dries?
I’ve made the positive with clay, and I’m going to cover it with vaseline and take a negative mold of it with plaster. My question is referring to the next part. I want to make a positive from the already dried plaster negative. I need to know, if the plaster of the positive being made will stick to the negative at any point and if I need to take any precautions, like vaseline or something. Thanks!
To stick: you need to rough up the texture of the plaster that you want to add on to. If it is too smooth, eventually the newer layer will break off of the previous layer. This is something you might do if you were building the layers for your mold and needed to add on after a layer had set.
To prevent sticking: this is for your next part>>>what you want is called a release. You can buy a can of Universal Spray Release, use vaseline in a thin coat, or mold soap. There are many types, just look up plaster and release. Vaseline can be applied with a chip brush, and mold soap can be thinned and applied with water, but you let it soak in and do a couple layers. If you use Murphy’s oil soap or green soap, use 1:1 water and soap, but you have to watch for bubbles. You can use an air compressor hose to blow those off. Some prefer the mold soaps and green soap because of the greasiness in other releases preventing absorption. The other thing to watch for, but this is at the beginning of moldmaking: make sure you placed your parting lines well so you don’t have any draft problems or undercuts aka problems with mechanically locking the mold to the casting.
I threw the Douglas & Sturgess link below. No matter where you are, you can call them and chat them up on their supplies and techniques.
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Posted by Yarock
February 10, 2010 @ 8:09 pm
It will stick on its own
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Posted by Tony89250
February 10, 2010 @ 8:35 pm
yeah it should stick!
References :
Posted by SXXY M&M
February 10, 2010 @ 9:15 pm
sure why wouldn’t it
References :
Posted by Cory D
February 10, 2010 @ 9:32 pm
Yes it will. Frescoes are made by sticking wet plaster to dry plaster and painting the wet plaster. Your question certainly makes sense, because wet ceramic does not stick to fired ceramic, so it would be reasonable to wonder if plaster works the same way.
It would probably be a better idea to make your negative out of something that’s not plaster in the future, if you want plaster to be the final product. Perhaps wax.
Vaseline might work keeping a plaster mold of the final product, but if there are any thin or bare spots, you will have blemishes where the final product stuck to the mold.
References :
Posted by margaretannem8s
February 10, 2010 @ 10:19 pm
To stick: you need to rough up the texture of the plaster that you want to add on to. If it is too smooth, eventually the newer layer will break off of the previous layer. This is something you might do if you were building the layers for your mold and needed to add on after a layer had set.
To prevent sticking: this is for your next part>>>what you want is called a release. You can buy a can of Universal Spray Release, use vaseline in a thin coat, or mold soap. There are many types, just look up plaster and release. Vaseline can be applied with a chip brush, and mold soap can be thinned and applied with water, but you let it soak in and do a couple layers. If you use Murphy’s oil soap or green soap, use 1:1 water and soap, but you have to watch for bubbles. You can use an air compressor hose to blow those off. Some prefer the mold soaps and green soap because of the greasiness in other releases preventing absorption. The other thing to watch for, but this is at the beginning of moldmaking: make sure you placed your parting lines well so you don’t have any draft problems or undercuts aka problems with mechanically locking the mold to the casting.
I threw the Douglas & Sturgess link below. No matter where you are, you can call them and chat them up on their supplies and techniques.
References :
Article; mentions parting compound aka "release":
http://www.ceramicartsdaily.org/ASSETS/B6F7353915154D8BBDD8930AD0FF9696/pmimayjune08_inthemix.pdf
for rubbers and plastics:
http://www.smoothonsecure.com/store/index.php?cPath=66
See their listing for potter’s soap if you’re doing ceramics. This is my favorite shop in SFO area:
http://artstuf.com/DStockNEW.fm$FIND?catsearch=MRA&header=CatHead&footer=CatFoot&html=CatShelf&sort=SKU
Posted by mike1942f
February 10, 2010 @ 10:32 pm
You need to use a separator – English Soap is traditional, but vaseline and spray fat (Pam) also work nicely. Plaster sticks to plaster and can be used to build up a model that has been carved too far, etc.
References :