Will my non-silicone waste mold idea work?

nick daring

Master Member

RPF PREMIUM MEMBER

• Dec 1, 2012

• #1

I hate blowing a bunch silicone on a mold that will only be used to make one intermediate part but I need to make less delicate resin versions of a couple parts.

The parts in question-

The hole on the smaller piece has been filled in since this photo was taken.

I was thinking about making 2 part plaster molds of each. I can split the smaller part vertically without any undercuts and the larger part should be able to split either horizontal or vertically without undercuts.

Can I take those plaster molds, clear coat the insides, shoot a little release spray and rotocast some smooth-on 65D inside and get a decent resin part that I can carve and sand my final detailing into without using silicone?

A slightly imperfect parting seem is not to big a deal.

Nick

 

Luke0312

Sr Member

RPF PREMIUM MEMBER

• Dec 1, 2012

• #2

Have you considered silicone caulk molds?

Obviously doesn't produce a cast as well as silicone made for molding and a little bit more frustrating to work with, but would probably be about the same cost once you add in a mother mold for it. Also would be less work to cast into.

 

S

Simple

Well-Known Member

• Dec 1, 2012

• #3

I agree the caulk mold might be a good idea. I've used caulk for one time molds of masters I needed to make delicate changes to.

C

 

BrundelFly

Master Member

RPF PREMIUM MEMBER

• Dec 1, 2012

• #4

Try this.
Get some thixotropic (thickener) for your silcone.
BRush it over your part, THEN mold it in plaster.

You will use a tiny bit of silicone, have nice results, and not break the bank.

 

fettster

Sr Member

• Dec 1, 2012

• #5

I make waste mould out of straight plaster all the time. As long as there is no undercuts, you'll have no problems

 

nick daring

Master Member

RPF PREMIUM MEMBER

• Dec 1, 2012

• #6

Do you have to seal the plaster before dumping in your resin or will a good spray of release do alright?

Nick

 

Tarchinoko

Well-Known Member

• Dec 2, 2012

• #7

you thought of using alginate? its a time sensitive way of making a waste mold, mix with water and let it dry and its like a rubber mold! but you need to cast into it fairly quick because after like 6 hours it starts to break down... super cheap tho!

 

robstyle

Master Member

• Dec 2, 2012

• #8

Just keep in mind whatever you do could end up being wasted time, money and the master part by trying to cut too many corners. Also consider the fact the end parts quality result. Your looking to pour resin into a mold thats made of a material in which water is involved. Water contamination is an arch nemesis for resin.
Why risk it?
Stick with a brush up of silicone backed with a hard jacket.

 

BrundelFly

Master Member

RPF PREMIUM MEMBER

• Dec 2, 2012

• #9

robstyle said:

Just keep in mind whatever you do could end up being wasted time, money and the master part by trying to cut too many corners. Also consider the fact the end parts quality result. Your looking to pour resin into a mold thats made of a material in which water is involved. Water contamination is an arch nemesis for resin.
Why risk it?
Stick with a brush up of silicone backed with a hard jacket.

Click to expand...

That is what I was thinking!


"Never enough time or money to do it right, always enough to do it over"

 

fettster

Sr Member

• Dec 2, 2012

• #10

nick daring said:

Do you have to seal the plaster before dumping in your resin or will a good spray of release do alright?

Nick

Click to expand...

its best to seal the plaster, couple of coats of spray lacquer and a couple of coats of wax and your good to go

 

nick daring

Master Member

RPF PREMIUM MEMBER

• Dec 2, 2012

• #11

Thanks for all the advice guys!

I'll try a plaster mold on the small part and see how it goes. It'll be fun to just experiment with the process even if it fails. Wasted time is also a lesson learned and this project has been all about learning new methods.

Brushing on some silicone will be my backup if it goes belly up.

I'll post my results once the testing phase has been completed.

Nick