This file is one of the Wolfstone archives of the Halloween mailing lists. You can find out more, and reach the entire collection here: http://www.pobox.com/~wolfstone/_r/HalloweenArchive.html This is a copy of Don Bertino's archive from http://www.calweb.com/~bertino/halloween.html on the subject of "plaster casting". Minor changes have been made, mostly removal of E-mail headers and signatures, but the germane content is unchanged. - - Date: Tue, 25 Jul 1995 08:13:58 -0700 From: milwiron at ix.netcom.com (D.D. ) Subject: Sealing plaster castings Howdy All, I've made large silicone rubber molds from a skull and jaw prop and am using it to cast a bunch of plaster (Ultracal) copies. Can anyone suggest a good sealer that will not darken the plaster? Clear lacquers and other clear paints tend to darken the surface. I'd like to seal it so I can then apply a stain in some areas (teeth, eye sockets etc.) and wipe off the excess. Without a sealer the stain just soaks in and can not be wiped off the high spots. I've used this staining process on other items made of plastic and have seen it used on plaster items before. - - Date: Tue, 25 Jul 1995 10:38:54 -0700 (PDT) From: Don Bertino Subject: Re: Sealing plaster castings On Tue, 25 Jul 1995, D.D. wrote: Hi Denny! > I've made large silicone rubber molds from a skull and jaw prop > and am using it to cast a bunch of plaster (Ultracal) copies. Can > anyone suggest a good sealer that will not darken the plaster? > Clear lacquers and other clear paints tend to darken the surface. > I'd like to seal it so I can then apply a stain in some areas > (teeth, eye sockets etc.) and wipe off the excess. Without a > sealer the stain just soaks in and can not be wiped off the high > spots. I've used this staining process on other items made of > plastic and have seen it used on plaster items before. I have a home a pattern book/woodworking catalog at home that has non-yellowing clear varnish. (Around $35 a gallon, ouch!) I have not (yet! :) worked with plaster, but what if you painted it white before hand? Or find a white that is plaster white? - - Date: Wed, 26 Jul 1995 19:41:40 -0400 (EDT) From: "Donna J. Logan" Subject: Re: Sealing plaster castings Dental labs use die sealer on their plaster dies which is basically a clear nail polish/cyanoacrilate (Krazy Glue) mixture....makes the die hard as stone and the brands I've used didn't darken the die. You could try to find a local dental supply store, or just try straight cyanoacrilate (I'd hesitate to suggest clear nail polish by itself, as the majority of nail polishes you'd get at a retail establish have nail conditioners, etc. added). Donna ;-> On Tue, 25 Jul 1995, D.D. wrote: > > Howdy All, > I've made large silicone rubber molds from a skull and jaw prop > and am using it to cast a bunch of plaster (Ultracal) copies. Can > anyone suggest a good sealer that will not darken the plaster? > Clear lacquers and other clear paints tend to darken the surface. > I'd like to seal it so I can then apply a stain in some areas > (teeth, eye sockets etc.) and wipe off the excess. Without a > sealer the stain just soaks in and can not be wiped off the high > spots. I've used this staining process on other items made of > plastic and have seen it used on plaster items before. - - Date: Mon, 31 Jul 1995 13:07:29 -0700 From: milwiron at ix.netcom.com (D.D. ) Subject: RE: Sealing plaster castings Hey All, Thanks to those of you who suggested some sealers for the cast plaster skull sets I'm working on. I posted the same question over on the news group and got an idea from Elsa Riedel. Her suggestion was to try Thompson's Water Sealer. I'm happy to say it works, it's cheap and it doesn't darken the plaster as much as other sealers. Denny P.S. Any ideas on a chemical that will speed up the hardening time of plasters? I know vinegar will slow it down. Rotocasting a 25lb. mold for 20 minutes by hand gets a bit old, uh...o.k., maybe it's me that's getting a bit old. - - Date: Mon, 31 Jul 1995 19:30:46 -0400 (EDT) From: "Donna J. Logan" Subject: RE: Sealing plaster castings Using hot instead of cold water speeds up the set time...but anything you use to speed set time also degrades the strength of the final cast ...something you may want to keep in mind depending on what use you want to use the cast for. ;-> On Mon, 31 Jul 1995, D.D. wrote: > > Hey All, > Thanks to those of you who suggested some sealers for the cast > plaster skull sets I'm working on. > I posted the same question over on the news group > and got an idea from Elsa Riedel. Her suggestion was to try Thompson's > Water Sealer. I'm happy to say it works, it's cheap and it doesn't > darken the plaster as much as other sealers. > Denny > > P.S. > Any ideas on a chemical that will speed up the hardening time of > plasters? I know vinegar will slow it down. Rotocasting a 25lb. mold > for 20 minutes by hand gets a bit old, uh...o.k., maybe it's me that's > getting a bit old. - - Date: Wed, 2 Aug 95 08:15 PDT From: bdosfx at wimsey.com (Brian Oberquell) Subject: RE: Sealing plaster castings >On Mon, 31 Jul 1995, D.D. wrote: >> Any ideas on a chemical that will speed up the hardening time of >> plasters? I know vinegar will slow it down. Rotocasting a 25lb. mold >> for 20 minutes by hand gets a bit old, uh...o.k., maybe it's me that's >> getting a bit old. Ordinary table salt added to plaster speeds up the set time, but the rule about strength reduction still applies... - -