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More Molding Tips
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Jeanette Lewis



Joined: 13 Oct 2009
Posts: 595
Location: Merseyside U.K.

PostPosted: Sat Oct 27, 2012 6:07 am    Post subject: Reply with quote

Hi Heidi,
I was wondering what release agent you use between the Rubber shim walls. They look quite textured and complex - but necessaray to reduce fins.
I have used soft soap on condensation cure; but that is a bit hit and miss. I'd like to put some locking elements into the rubber shims, to prevent fins and mis-alignments - so a good release agent would be pretty vital and helpful to do this.
Thanks Jeanette
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David Kim



Joined: 22 Feb 2013
Posts: 23
Location: Chicago, IL

PostPosted: Sat Mar 09, 2013 8:13 pm    Post subject: Reply with quote

Wow! This is great. I plan to try this on the portrait sculpture I'm working on now.
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Sandy Deane



Joined: 05 Apr 2010
Posts: 38
Location: Australia

PostPosted: Mon Mar 11, 2013 2:13 am    Post subject: More molding tips Reply with quote

This is wonderful info, to have this method so finely tuned, thanks for sharing, I am going to use this for my first ever mold Razz
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Phil Minchinton



Joined: 02 Mar 2009
Posts: 190
Location: London, UK

PostPosted: Mon Mar 11, 2013 4:55 am    Post subject: Reply with quote

Jeanette, a thin wipe of vaseline onto the rubber and into the locking points will do the trick. Once the second side is moulded it's easy to wipe off.
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Sandy Deane



Joined: 05 Apr 2010
Posts: 38
Location: Australia

PostPosted: Sun Apr 07, 2013 4:25 pm    Post subject: More molding tips Reply with quote

Your casts look immaculate Heidi. I have made a couple of casts now and I find the seam line very problematic. It is impossible to fix the aquaresin (i finally found a supplier over here ) cast so that it looks perfect.
I guess it follows that the better the mould the more perfect the seam line, but surely there is always some touching up to do?
I demoulded early so that I could work the resin whilst still softish.

When you have a free moment, do you have any tips?

Thanks again for this excellent post.
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Heidi Maiers
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Joined: 23 Feb 2005
Posts: 1223
Location: Near Portland OR

PostPosted: Mon Apr 08, 2013 12:01 pm    Post subject: Reply with quote

Sorry Jeanette that I missed your question back in October - I was moving that month and spaced a lot of things!
I am a pretty sloppy moldmaker, but it is important that your sections of rubber do not stick together at the shim line. I've used Dawn liquid dish soap with pretty good results. Just paint it on with a small paint brush and let it dry.
Sandy, I've never used aquaresin, so don't know how easy it is to repair. Any of the other resins I've used are a bit tricky, so that stuff is probably similar. Depending on the surface, you may be able to mix tiny amounts to do the repair and then sand or tool when set to make a smooth transition. Or use a material like magic sculpt if you are going to put an opaque patina on it of some sort. True that most will require touch up of some sort and it's easier to shave off imperfections than try to fill them and seams usually leave a bit of excess, making the process pretty easy as long as both sides line up properly.
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Jeanette Lewis



Joined: 13 Oct 2009
Posts: 595
Location: Merseyside U.K.

PostPosted: Wed Apr 17, 2013 8:29 am    Post subject: Reply with quote

Thanks for the reply Heidi, hope your move went well!
In the meantime I took Phil's advice but rather remiss of me forgot to thank him for it at the time - probably got distracted with the deadline looming...(apologies Phil) The Vaseline worked a treat! Very Happy
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Jeanette Lewis



Joined: 13 Oct 2009
Posts: 595
Location: Merseyside U.K.

PostPosted: Wed Sep 11, 2013 4:25 am    Post subject: Reply with quote

Hi Heidi,
Is it always best to keep the joins on a rubber mold dead vertical?
I think I read somewhere about the mold joins having to follow the most protruding lines of the mold - or is that for plaster waste molds?
feeling a bit confused before sectioning off my latest figure sculpt, so thanks for your advice.
Jeanette
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Tamara



Joined: 20 Oct 2005
Posts: 954
Location: Northern California

PostPosted: Wed Sep 11, 2013 9:10 am    Post subject: Reply with quote

Hi Jeanette,

I want to hear Heidi's response too but in the meantime, here's a tutorial on my blog showing some of my partitions horizontal or diagonal. http://tamarabonet.com/blog/2011/12/06/dreamer-mold/#more-1170

It's more difficult to do them at an angle because you have to support the clay walls creatively. Smile

Hope all goes well with your latest project.

~Tamara
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Heidi Maiers
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Joined: 23 Feb 2005
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Location: Near Portland OR

PostPosted: Wed Sep 11, 2013 9:12 am    Post subject: Reply with quote

I don't think seam direction really matters. Depends on the sculpture and how many sectons you need to make. Complicated sculptures are usually cut into several pieces and molds made for each, then welded together after each section is cast (in the case of bronze). For a simple head, you can usually make a one piece mold with a seam going up the back. A figure becomes more complicated, especially if there are spaces between arms and legs that would lock a mold on. Just have to study the sculpture and visualize where it makes sense to make the seams - horizontal, vertical, and anywhere in between goes - even zig zag for that matter, if it makes sense to do so.
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Heidi Maiers
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PostPosted: Wed Sep 11, 2013 9:17 am    Post subject: Reply with quote

Ah, we posted at the same time Tamara!
I agree about the clay walls, if that is the shim method you are using. They are tough to keep in place if you are fighting gravity. On horizontal seams, you can try using metal shims (cut up aluminum cans or sheets of thin aluminum), or even plastic milk jugs. about 1 inch wide by 2 or 3 inches long. These can be stuck in the clay overlapping each just slightly, along the shim line. The seam is not as clean using this method, but it sure stays in place better and makes the mold making easier.
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Tamara



Joined: 20 Oct 2005
Posts: 954
Location: Northern California

PostPosted: Wed Sep 11, 2013 9:34 am    Post subject: Reply with quote

Ah, well, we didn't contradict each other too much! Ha, ha!

I saw at Artworks Foundry, that they were using a stack of playing cards to stick in along the seam line. Was on a larger sculpt (maybe 4ft or so). Worked for them but I don't like sticking anything into my clay original (other than the t-pins that I must stick in to hold up the clay walls). I try to save and fire my sculpt later. Wink
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Jeanette Lewis



Joined: 13 Oct 2009
Posts: 595
Location: Merseyside U.K.

PostPosted: Thu Sep 12, 2013 9:06 am    Post subject: Reply with quote

Thanks for your answers Heidi and Tamara,
You've both inspired me to try and be more confident with tackling mold seams - Great to see the mold process in stages like that Tamara; looks masterful! Smile
I've tried the metal shim approach, and found it works better on larger pieces as it doesn't chew up the original clay too much.
Wondered if you had heard of the following approach?
I spoke to a prosthetics maker the other day; he suggested smoothing the outer layer of the silicone before creating the mother mold - by covering ones hands with washing up liquid and applying to the surface of the silicone -( I guess while it is still in the green and hasn't set) Can't see how location lugs would/could be attached using that method - (perhaps his work tended to be flatter - low relief) anyway I've not tried it yet, perhaps I will on something smaller than my present piece to see how it goes.
Food for thought though. Smile
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Tamara



Joined: 20 Oct 2005
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Location: Northern California

PostPosted: Thu Sep 12, 2013 7:01 pm    Post subject: Reply with quote

Glad my mold tutorial was helpful. Smile I have a few other mold tutorials on there as well.

Haven't tried using dishwashing soap to smooth the last layer of silicone. Nice to know other ways of doing stuff. Smile I've been using a runny coat of silicone without cabosil (or other thickening agent) to smooth out bumpiness. Having some bumps (and keys) actually helps the silicone to stay in place inside the mother mold.
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Jeanette Lewis



Joined: 13 Oct 2009
Posts: 595
Location: Merseyside U.K.

PostPosted: Fri Sep 13, 2013 2:58 am    Post subject: Reply with quote

Hi Tamara,
I thought this too about some bumpiness being helpful - I am wondering if his concern was with making the inner surface of the mother mold smoother (if using fibreglass resin) so that if you use a thin as possible layer of soft grade silicone - it will not bulge into any "gaps" when the weight of the substrate material is poured or pressed in.
I should think your using a combination of plaster and fibreglass has a much smoother inner surface than a fibreglass resin.
Well, it seemed an interesting way of smoothing silicone ..perhaps, I suppose I could go visit him one day and ask!
http://www.makeupsfx.com - Hmm make up effects for T.V. - not sure the techniques would be interchangeable. Smile
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