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Hitch Senior Member

Joined: 16 Jan 2006 Posts: 2429 Location: Somerset
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Posted: Sat Jul 12, 2008 2:20 pm Post subject: Casts |
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I have been asked to do a plaster casting for someone.
Ive got what will be used as a mould, thick vacum formed plastic, just need to knock up a frame to keep the edges straight.
I need something that will let the plaster come out with ease, but wont inhibit painting of he finished item. I imagine spray silicone grease or similar would be ideal, but would make it difficult to paint...
Anyone done this sort of thing before? _________________ Why isn't the number 11 pronounced onety one? |
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Hoovie Devon DIYer

Joined: 27 Jul 2007 Posts: 7773 Location: East Devon
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Posted: Sat Jul 12, 2008 3:05 pm Post subject: |
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How about PTFE Spray applied just before the pour? _________________ If you have a son, DO NOT name him after a verb ....
"Neil, Standup. Neil, Standup"
"Which is it, man?" |
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thescruff Senior Member

Joined: 10 Mar 2008 Posts: 4658 Location: Bath
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Posted: Sat Jul 12, 2008 3:15 pm Post subject: |
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I would try one without anything first. It should just pop out when you turn it upside down. _________________ Scruff |
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Wood Magnet Senior Member

Joined: 07 Feb 2006 Posts: 3550 Location: sunderland
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Posted: Sat Jul 12, 2008 5:51 pm Post subject: |
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cliing film  _________________ People forget how fast you did a job - but they remember how well you did it.
I no longer skinny dip, i chunky dunk these day's. |
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leebwk Senior Member

Joined: 01 Dec 2006 Posts: 827 Location: Oxford
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Posted: Sun Jul 13, 2008 10:16 am Post subject: |
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Maybe anything thats water based and can be wiped down after _________________ What was the best thing before sliced bread? |
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ultimatehandyman Site Admin

Joined: 16 Jul 2005 Posts: 9278 Location: Darwen, Lancashire
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Posted: Sun Jul 13, 2008 10:37 am Post subject: |
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I bet Victor has done this before, I am sure he will know what is best to use. _________________ DIY | DIY Video |
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joiner_uk Senior Member

Joined: 08 Apr 2008 Posts: 256 Location: Sheffield
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Posted: Sun Jul 13, 2008 7:26 pm Post subject: |
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Fairy liquid but thats just a guess, well it works with cement  _________________ Carpenter & Joiner Sheffield |
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Hitch Senior Member

Joined: 16 Jan 2006 Posts: 2429 Location: Somerset
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Posted: Tue Jul 15, 2008 5:33 pm Post subject: |
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Well, in the end, i went with a very light squirt of dashboard shine, on a cloth. Turned it out tonight, a few pats with palm of my hand and out it came. Nice and smooth.
A very light rubdown before painting hopefully will get rid of any remains of the silicones prior to painting.
Reckon i'll need to leave it about a week or more before its fully dried. _________________ Why isn't the number 11 pronounced onety one? |
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rotciv Senior Member

Joined: 05 Apr 2008 Posts: 322 Location: Malta
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Posted: Fri Aug 15, 2008 11:44 am Post subject: Re: Casts |
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| Hitch wrote: |
I have been asked to do a plaster casting for someone.
Ive got what will be used as a mould, thick vacum formed plastic, just need to knock up a frame to keep the edges straight.
I need something that will let the plaster come out with ease, but wont inhibit painting of he finished item. I imagine spray silicone grease or similar would be ideal, but would make it difficult to paint...
Anyone done this sort of thing before? |
i have made plaster moulds of several objects made from different materials. in your case a brush over the mold of undiluted dishwashing soap would probably do the trick. i have even used turtle wax car polish as a parting agent between plaster and plaster.
victor _________________ Dreams contain the seed of success..... (if you manage to wake up.) |
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