hey everyone!

i could use some advice.. i'm working on a sculpt, and the angle of the head (the back of the head, specifically) is going to make a pretty severe undercut when it comes time for molding and casting. could you take a look at these pix and troubleshoot this with me? how would you deal with it?
thanks much,

matt

From my very limited experience I would suggest doing a multiple part mold, since I'm assuming that cutting it up isn't an option. I suggest at least doing your mold in four parts. that way you can easily remove the piece from the mold... anyone more knowledgeable please chime in...

Okay first off that piece is gorgeous! So clean and crisp and the anatomy work is just top notch! Fantastic!

Secondly, I honestly don't really see any major issue here doing a 2 part mold. Assuming I'm looking at the finished piece, I don't think you're going to have any problems so long as when you make the mold you add a vent that runs parallel to his neck and connects the back of his skull to the mass of his shoulders. Make the mold so that when it's time for the resin it's getting poured upside down with the large shoulder mass as the pour spout on top and the head section at the bottom. Wnen you add the vent that connects the back of his skull to his shoulders you'll get rid of any air bubbles that would be trapped in that undercut shape of the skull and you should be golden. Let me know if you'd like me to make a quick sketch for you if I'm not being clear enough with just my words. This stuff is kinda hard to communicate sometimes.

Good luck and again that is such a wonderful piece!

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Edited by Professor Oreo on Jul 2, 2010 at 03:34 AM

maddmaestro: doing a 4 part mold is an interesting idea, that hadn't occurred to me. that would help for demolding, but unless i'm misunderstanding, it would still leave me with a big air pocket at the back of the head when i pour..

professor oreo: thanks so much, i'm glad you like it! it's mostly finished, i just have a bunch more detailing and texturing to do.. i've never made a vent in a mold before, how would you suggest i go about it? would i drill into the silicone after it's set? and how would i go about demolding when there's a triangle of negative space created by the vent? i would love to see a sketch of what you mean if it's not too much trouble..

thanks so much for the responses, guys!

Okay here's kinda what I mean. The tube coming off the back of his head is the vent and the dotted line is a suggestion as to where you would place the parting line for a two part mold. For my vents I generally use circular wooden dowels. So I either embed the wodden dowel where I want it in the the clay when I'm clay-walling the first half of the mold, or I'll just hot glue weld it to the spot on the sculpture if the vent is not going to coincide with the parting of the mold line.

If you plan the mold so that the parting seam runs along the vent then you won't have any problem removing the piece from the mold. If the vent is fully encased in silicon it's not really a problem either. You should be still able to release one side of the mold completely and the other side with the vent will be locked into the silicone. Bend the silicone away from where the vent connects to the sculpture and trim it with a wire cutter while the piece is still in the mold. You should then be able to demold the rest of the sculpture and then remove the resin trapped in the vent from the other side thru its airspout.

I know that probably makes zero sense but it's a very tough thing to describe without being in the same room with you to show you. Hopefully you're able to understand kinda what I'm talking about. :)

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Mattlev

What up , this thing is awesome. These guys know about molding , thanks guys, good thread. Let us know what happens , with pics!

j

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Lisa Raye

okay, prof..
i've been staring at the picture with your marks on if for a while now, trying to wrap my head around it. i get the vent now, that's not a problem. i had thought that you were saying it should go from the back of the head to the mass of the shoulders.. but it going straight out of the mold makes good sense.
the thing i'm looking at now in your image is the parting line to make it a 2 piece mold. the face area is confusing me a bit.
i guess i look at it and worry it would be too difficult to access to clean and prep between castings, and that the extent i'd have to bend the mold to demold each time would drastically shorten the life of the mold. (i said "mold" 3 times in that sentence.) um... mold.

what about this...


i added an extra line along the jaw line to make it a 3 piece.. is this unnecessary? am i just being silly, and the 2 piece mold won't actually create any problems at all? i would totally rather make a 2 piece mold than a 3 piece; after all, the less steps there are, the less opportunity for me to mess up.

thanks again for your continued help!

---------------
hey, jarrod! thanks, see you in a few weeks!

The sculpt is sick!

Walter clearly knows WAY more about moldmaking than I do. Carry on.

B

Mattlev, Yeah you could certainly make a 3 part mold if you think it would help you crank thru these faster as far as demolding and prepping the mold again for another pour.

Personally I hate cleaning up seams on my castings so the fewer parts to the mold the better in my opinion. If you do it somewhat like I suggested you'll have to put in some extra effort to demold each casting as you'll certainly be flexing the mold a bit to get it to pop out, but the seams on each casting should be in places that are easy to access but overall not very crucial to the visual impact of the piece. If you have a seam that breaks across his chin that's much more of a vital area that you may not want to have to carve down, putty, or resculpt depending on how clean the mold turns out.

As far as the parting lines across his neck and shoulders – place those anywhere you want to make the resulting shape of the mold easier to deal with. Maybe you want the mold to split closer to the center of his chest and the other side to split up his back? Figure out a place where he seam is going to do the least amount of damage to the piece in a spot where it’s going to be easy to repair and split the mold there. That’s what I usually try to shoot for.

If you're worried about the mold tearing during the process you should choose a tougher silicone with a higher tear strength so over-flexing it won't be an issue. Those types of silicone can be a bit more expensive but if you are planning to crank out several copies of this piece than you may want to go that route anyway as those higher tear strength silicones tend to have a much longer library life.

But yeah man it's kinda tough to talk thru this stuff over a piece with an odd shape without seeing the piece in person, so you would know best how to tackle the problem because you're the only one who has actually seen it. So please take anything I suggest with a huge grain of salt because I only have a limited frame of reference for this piece and you've got a much better idea of what you're dealing with here than I do.

Good luck to you! And if I can be of any more help please let me know!

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i'm going to pick up the silicone this morning.. thanks for all the help, i'll let you know how it goes!

Hey Matt!

Great sculpt man - really nice!

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Norman Meyers
http://artistproofstudio.blogspot.com

thats a bad ass sculpt man !!!!!!!!!!

awsome !

r

oh yea ,,,duh ,,the advice given is 100% solid :)
fo sho !

r

hey everyone,

thanks again for all the advice and support!

the deed is done, this might get a bit pic heavy...

i'm gonna give a bit too much info here, and hope that someone will find it interesting or helpful.
so i went with a two part mold, figuring 1, it would be easier, and 2, it would mean i would have to cover much less of the sculpt with clay, which sounded good because that's less clay i'd have to worry about removing without hurting the original. i really wasn't sure how much of a problem that would be since this was my first time making a mold from chavant.

building up the clay for the 1st part of the mold..


making the walls..


another view. if only i had known how problematic the head would become..


first part of the mold done. taking the clay out from the head area was nearly impossible. especially the area near the ears. the angle was so severe i couldn't even see in there and had to close my eyes and dig in with a finger trying to feel the difference in texture between the chavant and the water based clay i was using to make the mold. and the only way i could get my hand in to do even that was to remove one of the walls and pray that it would re-seal well enough to the silicone that the second pour wouldn't end up being a really expensive puddle on the table.. oh, and i sawed up a paintbrush handle to make the air vent.


2nd part poured. you can see i ended up having not quite enough silicone to pour all the way to the top; luckily, it was enough. it looks a bit lumpy because in an attempt to be thrifty, i cut up an old mold so i wouldn't need as much silicone. that stuff is stupid expensive.


the first pour!


this pic is just cause i like depth of field..


demolding.


the first raw cast..




cleaning was a bit of a chore, there were some problem areas, partly because i turned out i never did manage to get all that clay out from around the ears.. so i had to sand a bit, dremel a bit, magic sculpt a bit, and then sand again. oh well...
and then i painted him and bolted him to a game head panel.



so that's that.. i've poured 2 so far, and i figure i'll just keep going until i run out of resin.
if you want one, let me know..
thanks for reading!

The finished product is excellent mattlev!

Thanks for posting as many pics of process as you have, (though I'm hoping you might post a few more soon, especially a face-on pic). I love the plaque mounting... Gives a creepy taxidermy/trophy feel to it.

On my budget, I'd probably try the same idea of adding scrap mold as filler. Any problems with that? Is the mold just as strong this way?

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Thanks 9thmonk!

glad you liked the process pix..

this was the first time i tried using scrap mold, it was suggested to me a while back by king unicorn. i wasn't sure of the best way to go about it, so i just made it up as i went along, and tried to make sure that the scrap silicone didn't actually touch the sculpt, but for all i know that wouldn't have been a problem anyway.. what i did was mix up a batch of silicone, pour half, then push the old chunks into what i had poured, then pour the other half of the fresh silicone on top of it. it seems to be strong, i'll have to wait and see how it ages as i pour more casts..

here are some face pix of the original. that painted one is gone. i ordered some more wood plaques, and i'll start painting more once they arrive.

hi again!

some photos of the final paint job are up at my website.
http://www.matthewjlevin.com/allow-me-to-introduce
i was going to put the pictures here, but now that flickr won't let me do that anymore, i'm not sure how to get them up here.

anyway, enjoy!

Really amazing sculpt Matt!
Great to see your molding and casting process.

The final painted piece looks fantastic!

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Norman Meyers
http://artistproofstudio.blogspot.com

thanks norm!

i saw your new painted piece on the facebooks this morning, it looks awesome!

wow. thats one of the coolest pieces ive ever seen!