Fiberglass and mold making question

[Greg Austin]

Im trying to make a mother mold for a sculpture I made and its for a silicone mask im making, Ive seen youtube videos and Neil Gortons videos where they 1st lay down a gelcoat over the sculpture to pick up all the detail then fiberglass the rest, my question is the fiberglass resin the gelcoat ? I just bought some Bondo fiberglass resin from Auto Zoneand wanted to know if I just put a few layers of the resin on the clay before the fiberglass matting will the few layers pickup the detail of my sculpture like the wrinkles in cracks of skin ? please help

 

[pitchforknumb]

The problem with just using resin is that it's really runny and hard to not have pool in areas. I like to mix body filler with the fiberglass resin to capture the beauty layer. You can mix them to as thick as you need it, and really works well with capturing detail.

 

[Greg Austin]

Thanks for the advic, My sculpture is a zombie with a lot of hanging skin and I feel like if it was runny then it could get in the detail better ? Idk but have you or anyone else just captured sculpture detail with just liquid resin backed by fiberglass mat ?

 

[Greg Austin]

Anyone ?

 

[Friko]

The problem with just using resin is that it's really runny and hard to not have pool in areas. I like to mike body filler with the fiberglass resin to capture the beauty layer. You can mix them to as thick as you need it, and really works well with capturing detail.

I too use a bondo-resin mix. Mix it to where its a little thinner than tooth paste. You want it thin enough so it can capture all the details but not soo thin it will just run all over, and not too thick that it will create air bubbles in your details. It's a hit and miss game. Every mold will be different and once you get the hang of it you will know how to work it. And once you do get the hang of it you will never use plaster for molds again.

 

[CreatureFX]

Just do the bondo and resin mix to start. Do 2 layers of this, waiting for them to cure in between. Then start doing your fiberglass mat and resin.

 

[Greg Austin]

thank you, last question, what kind of bondo do I use ?who makes it ? whats it originally used for? like boats, cars? and is the bondo a liquid ?

 

[TigerStoneFX]

Why not just buy gelcoat resin? It saves making your own mud coats from filler.
Go to a marine supply store or FX store and get gelcoat resin, polyester resin and some mat. If youre wanting to capture detail and make your filled gelcoat too thick, you may lose details.
If this is your first time doing this, doing it the "normal" way is a good way to start.

 

[pitchforknumb]

Any kind of bondo that you get from Autozone will work. For the most part I use this kind 3M/1 qt. gold Dynatron Dyna Delite body filler (332Z) | Body Filler | AutoZone.com. Usually used on cars for repairing damaged areas. Bondo's not really a liquid. It has the consistency of peanut butter.

 

[CreatureFX]

The 3m stuff works fine. Remember do this outside and with a respirator! If your working with big batches get coveralls!

 

[Greg Austin]

thanks everyone, Yea I rather just do a gelcoat, is that strong enough to pickup all details like skin texture ? wrinkes ?

 

[CreatureFX]

Do two or more gelcoats, one isn't enough. The first one won't get everywhere and the second will get where the first didn't. Let us know how it works out!

 

[Dr Know]

I think that first, an important question would be...
What is the type of clay that You used for you sculpture?
The bondo/resin combo has a history coming from the world of taxidermy ...
Most started using the Bondo mix for molds due to it being more friendly with moisture. When a lot of sculptures were being done with WED clay.
Bondo is mostly talc thickened resin... So using the two catalysts it works ok. MEK-P for the resin.. And the red (white, or blue) catalyst for the Bondo.

Gel Coat works fine, and I usually spray my surface Gel-Coats..
Wait till it sets up completely..
Then mud and resin/glass... Mud consisting of poly-fibers thickened resin. Or cabosil can be used to thicken the resin. The mud coat smooths out and fills in the deeper areas so the matte can lay down easier... On a flatter surface.

Gel Coat will give you better seams with less clean up, but bondo/resin will do fine as well.

If using the bondo/resin mix? Just be cautious and not over catalyze the material.
Due to the excessive fillers, the bondo mix will be a bit less stable and has a tendency to warp pretty easily. Food for thought...

 

[Greg Austin]

Thanks Dr Know, The clay I use is Monster clay, Im going with the gelcoat, Does auto zone sell it ?

 

[pitchforknumb]

That's the problem with the gelcoat, is finding somewhere to buy it from. In my area the only place I could purchase it from wanted $90 for a quart, so I switched to the bondo/resin method because of that. You'll have to ask around your local marine hardware stores, or order it online.

 

[TigerStoneFX]

Do two or more gelcoats, one isn't enough. The first one won't get everywhere and the second will get where the first didn't. Let us know how it works out!

Wow the gelcoat you guys have over there must suck if you have to do 3 coats.

If you can afford it, the Smooth On Epoxy stuff is really good and the gelcoat (the red one) is very popular.

 

[CreatureFX]

Sometimes you don't have enough hands to get the material everywhere, before it cures on you, so a 2nd gelcoat is necessary.

 

[Dr Know]

Wow the gelcoat you guys have over there must suck if you have to do 3 coats.

If you can afford it, the Smooth On Epoxy stuff is really good and the gelcoat (the red one) is very popular.

The gel coat in the States is a bit more sensitive to moisture than the UK stuff... I have used both. But the Gel Coats work fine over here.
All comes down to experience and technique.
That is why I have sprayed my gel coats... I can do an entire body.. Standing up...all at once... Gel application time about 30 minutes for the whole mould.
Not one pin hole or bubble due to the spray application.
No need to even think about gravity due to the spray application.
It is a nice technique to have.

Greg... It does come down to where You live at times...
Looking for a distributor can be advantageous though...
5 gallons gel comes to around $120... And goes a LONG way.
Epoxy works, but is really expensive.
For a mould that will not run more than 15-20 times... Epoxy can be a waste of money IMO.

Look up companies like Rev-Chem... Or AP Products to name a couple...
Greg, You mentioned Monster Clay... Which has a high wax content. By that, you have to be mindful of the clays sensitivity to heat.
Are You planning on shimming? Or clay wall?

 

[Witchking]

This is a great thread. One question I have is when you mix the body filler with the resin, do you use the red bondo catalyst as well, or does it work better just to mix the raw bondo filler with resin and hardener?

 

[CreatureFX]

Use the catalyst for each of the products. The resin and the bondo.