Sasquatch and questions, questions, questions

[spookysully]

Hello, I did my first sculpture in 2008 and have been enjoying the craft ever since! I was hoping that I could pick the brains of some actual sculptors as I'm seeking someone with mold making experience that would be willing to share their wisdom with me.

I hope its ok that I put a link to my work up? This series has proven to be very popular and I have several orders for some of these pieces but am stumbling blindly along with no real hope of getting them filled.

http://sasculpture.blogspot.com/

Thanks for any help I can get!

Cheers, Cliff

[Andrew Werby]

So what are your questions, questions, questions?

Andrew Werby
Juxtamorph.com

[spookysully]

Well, I should explain that I apparently don't spend enough time in forums and forgot the; read through other posts before you post an already answered question etiquette. After helping myself to some other threads, I was able to get a few of my answers rather quickly!

I'm looking for mold making advice, advice of any kind would be helpful as I've only sort of done it once and it was with different materiel. I'm using a 2 part Platinum Silicone from Tap plastics currently. They gave me some horrible advice and not knowing, I followed it and almost lost one of my pieces. After an expensive lesson, I'm hoping that things will work out but I guess I won't know until I try. I'm freaking out because I just can't afford another idiotic mistake, this stuff is expensive and goes rather quickly!

If you've seen what it is that I'm doing, you'll see that there are some hurdles right off the bat concerning making molds that would have been easy to accommodate had I known what I was doing during the sculpting process, like broadening the hair striations. This has cost me many hours of work and hundreds of dollars but like I said, I just didn't know.

So, I figured that I would ask the experts, are there any tricks or things I need to know before I begin again. I know that most, if not all of the pieces will have to be 2 part molds which adds another step to get competent with before proceeding.

Thanks for replying! Cheers

[mantrid]

Why were you advised to broaden the hair striations? cant see why that would be necessary. Also these simple shapes you are moulding could easily be done with a one part inner mould with a slit up the back and a two part mother mould for support.

[spookysully]

When I was making the striations, I didn't know it but I was inadvertently creating a wider trench beneath the surface, then when I pulled the tool out, there was a thinner line left at the top of the hole.

When it was fired, each striation became a tomb for the silicone that made it in. When I tried to remove the silicone, 99% of the "hair" was torn off and left in the clay. I was also told that I didn't need a release agent which was obviously not true.

I bought a can of stoner release agent and smoothed the sculptures out and am almost ready to try again.

"Also these simple shapes you are moulding could easily be done with a one part inner mould with a slit up the back and a two part mother mould for support"
If you could expand upon this idea, I would love to hear it! Most of the pieces have a complete recess at the underarm which lead me to believe a one part mold wouldn't work but what do I know?Thank you so much for the reply!

Cheers

[spookysully]

I just took a closer look at your avatar and was wondering if you think it might be possible to do one of my pieces in bronze? How much would it cost? The piece I have in mind is "Montana Winter". Thanks in advance!

Cheers

[Andrew Werby]

Originally Posted by spookysully

When I was making the striations, I didn't know it but I was inadvertently creating a wider trench beneath the surface, then when I pulled the tool out, there was a thinner line left at the top of the hole.

[That sounds like what we call "undercuts". Silicone rubber is able to deal with minor undercuts, but it sounds like yours were major.]

When it was fired, each striation became a tomb for the silicone that made it in. When I tried to remove the silicone, 99% of the "hair" was torn off and left in the clay.

[The original was in fired clay? And it broke up due to demolding? I'm having a hard time picturing the "hair" left in the clay. Did you mean left in the rubber?]

I was also told that I didn't need a release agent which was obviously not true.

[Silicone rubbers don't stick to most things, but porous fired clay would probably be an exception. If you're making something to be molded, you don't really need to fire it.]


I bought a can of stoner release agent and smoothed the sculptures out and am almost ready to try again.

[Smoothed them out how? By grinding on the fired clay models?]

"Also these simple shapes you are moulding could easily be done with a one part inner mould with a slit up the back and a two part mother mould for support"
If you could expand upon this idea, I would love to hear it! Most of the pieces have a complete recess at the underarm which lead me to believe a one part mold wouldn't work but what do I know?Thank you so much for the reply!

Cheers

[What's a "complete recess"? You mean it goes from the front to the back? That can be filled in with rubber and split for demolding. How are you going about making these molds? Building it up in layers, or making a shell offset from the model and pouring rubber in to fill the gap?]

Andrew Werby
www.unitedartworks.com

[KatyL]

How thickly did you put it on? Unless the striations were like strands of spaghetti, and lifted off the surface, not much should have happened.

You are right-- you need to think of how to make the mold as you are working on the sculpture.

I make molds all the time. I'm just finishing up one tonight. I learned to always make my figure armatures strong enough so I can lay them over. I like clay walls better than metal shims. I use Silicon Inc's GI-184 plus GI-1000, and thixothropic catalists, and UFC to speed the process. Whatever rubber you use, just follow directions. I lay mine on or brush, not pour, I make a layer of about between 1/4th and 1/2 inch and then put a cheese cloth layer (with GI-1000 because it goes through the holes best) to stiffen the mold. Then I make the outer mother mold of plaster and burlap. I have also done a polyester resin and fiberglas mothermold. The mold can be bolstered with wood, metal, and auto-body filler.

I am trying to get better at laying up and walls. I have newly found uses for water-clay (pottery clay) to make initial disposable clay-walls (a hybrid clay offset type technique).

As far as the cost of bronze, all foundries seem to do things differently. You should find your nearby foundry and speak to them with some photos and measurements of your piece.

[spookysully]

I apologize as I'm not explaining this very well. The striations are wider at the bottom than at the top, picture a pitcher or vase full of silicone. I think undercut is exactly what I have.

The original pieces are all in clay and fired, the striations, being vase like (wide bottom, narrow top) all tear at the top when I pull the mold from the sculpture leaving all of the silicone "hair" stuck down underneath each striation due to the undercutting, leaving no detail in the mold. This of course doesn't happen on every striation but the percentage is so high that it might as well.

I'm now using a plasticine clay that I won't need to get fired and I can harvest the clay from the original and use it again and again as well as solving the striation problem toot sweet!

Yes, I smoothed each sculpture out to Hummel figurine smoothness and did my best to get rid of the undercutting as well by widening the striations at the top so the silicone can get back out once it has set up.

By complete recess I mean there is space between the inner bicep and the chest on some of the pieces that runs from the front to the back. The arm is just far enough away from the body to create this...tunnel? I guess you'd call it.

The way I'm doing it is, I first put a thin coat of silicone to capture the detail then add a thickener to a 50/50 mix of the Platinum Silicone and glop it on like peanut butter. I'm unsure what to call this method but it didn't work so I'll try whatever you think I should.

Cheers

[mantrid]

Im surprised silicone caught in the undercut of the hair and ripped off. You could try not making then so deep and or use a tool that doesnt create an excessive undercut or you could try a softer silicone in the first layer which would compress easier and pull out before ripping off. I think the easiest solution if you didnt want to do some remodelling would be to rub petroleum jelly over the piece using a blow lamp to melt it into the hair crevices. Dont use too much or it will fill the crevices. This will provide a very sippery surface so the silicone will pull out without resistance.

A thin channel going beneath the arm pit isnt a good idea when constructing a mould as it will result in a thin bridge of silicone. Half from one side of the mould and half from the other. It would be next to impossible for these floppy halves to meat exactly and stay in position while you pour in wax resin or what ever else you are casting with.

It would be best to fill the area and then you can do a one piece silicone mould with a slit up the back, which if you can visualise will come off like a hooded jacket on back to front.