Resin Casting Question

[Organic Mechanic]

OK, bear with the n00b for a moment here. :lol

I know exactly NILL about making castings, or even what a casting feels like. But it occurs to me that everything I've made so far has been sculpted from random bits. From reading around I realize that all I've really been doing is sculpting masters. Step 1 if you will. So I looked into mold making materials, and casting methods, compared it against the advice you all are so willingly sharing and decided that "Yes, I can do this."

There is one thing I still haven't quite put my finger on though.

Resin.

Man, that is about the vaguest term I've ever heard. What is it? Is it the material that I currently know as "Poly-Resin"? Y'know, the stuff they make those uber-hard, dense, el cheapo statuettes for places like Family Dollar from? Is it different than that? Easier to work with? Does it warp/expand/shrink with age? Is it particularly brittle?

etc., etc., etc.

I really appreciate any info you can give me here. I hate to go into something with no knowledge, y'know?

Thanks in advance, OM

 

[exoray]

There is one thing I still haven't quite put my finger on though.

Resin.

Man, that is about the vaguest term I've ever heard. What is it? Is it the material that I currently know as "Poly-Resin"? Y'know, the stuff they make those uber-hard, dense, el cheapo statuettes for places like Family Dollar from? Is it different than that? Easier to work with? Does it warp/expand/shrink with age? Is it particularly brittle?

Loaded question...

In this hobby resin will usually refer to a polyurethane casting resin...

But that is hardly the limit of resins, there are many other kinds that have their uses... Epoxy, polyester, vinylester, acrylic to name a few...

 

[Organic Mechanic]

Loaded question...

In this hobby resin will usually refer to a polyurethane casting resin...

But that is hardly the limit of resins, there are many other kinds that have their uses... Epoxy, polyester, vinylester, acrylic to name a few...

I see. Thank you very much. So I was making a good assumption (we all know how they work) at least. I am more than a little relieved to discover that it's a matter of choice, with so many options. There some things that standard Poly-Resin would be absolutely TERRIBLE for.

 

[modelnutz]

The standard resin used in the GK industry is called Urethane.
It's (typically) a 2 part resin.
I would direct you to smooth-on.com
Check out the resins they offer...many of their resins are designed for ease of mixing ( 1 to 1 ratio ) and you can get materials that will create anything from a rubber band hardness ( 20 A shore hardness ) to a bowling ball ( 80 D shore hardness )...many garage kits are made with their SC-300 and 305 resin. As for it's relation to the "poly" resin....it's typically much easier to work with and quite a bit less toxic ( you still need air transfer though...gotta get the fumes out of your work area...but, still nowhere near as bad as polyester resins)

( FYI.."shore hardness" is an industrial scale used to describe the surface hardness of materials...it relates to how deep a steel ball will push in to a surface after a drop from a given height )

well...there's a teaser for ya...along with a site for further study.
As you get more questions...ask away....I'm sure you'll get the help you're looking for here.

 

[Organic Mechanic]

You guys are great. I knew y'all would be able help. Thank you.



And I'm sure I'll have more questions as I get further into it.

 

[rollerboi]

Mind if I piggy-back on this thread?

I've been wondering what kind of resin to use to get a slightly rubbery kid's toy feel to an item, if you guys know what I mean.
I read about hardness but nothing really describes texture and feel that I've found.

 

[Organic Mechanic]

Can you give an example of a toy with the texture you seek?

 

[Funky]

I read about hardness but nothing really describes texture and feel that I've found.

That's what SHE said! :lol

Okay...I would start here: Model Making | Silicone Rubber, Urethane Rubber, Liquid Plastic, Casting Resin, Lifecasting, Epoxy Resin, Rigid and Flexible Foam from Smooth-On

 

[exoray]

Mind if I piggy-back on this thread?

I've been wondering what kind of resin to use to get a slightly rubbery kid's toy feel to an item, if you guys know what I mean.
I read about hardness but nothing really describes texture and feel that I've found.

Mileage will vary but in most cases you can custom blend, some stuff doesn't play nice but a majority of urethane resins will...

You can take a regular hard plastic like grade urethane casting resin and mix in a urethane casting rubber... Infinite possibilities and feels...

As for the texture a lot of that can be done pre-molding... A high gloss wet sanded original part will yield high gloss smooth castings, but on the other hand if you mist the part with say a flat paint prior to molding the resulting parts will have a satin like feel to them and will have a dull surface when cast...

 

[rollerboi]

Can you give an example of a toy with the texture you seek?

I really wish I could. I just have this mental image in my head of my final result, but not any current toys. I'll have to go to Toys R Us soon and fondle everything before being escorted out.

That's what SHE said! :lol
Okay...I would start here: Model Making | Silicone Rubber, Urethane Rubber, Liquid Plastic, Casting Resin, Lifecasting, Epoxy Resin, Rigid and Flexible Foam from Smooth-On

I was thinking that as I typed it! :lol And yes, I look at Smooth-On's website every couple of weeks for inspiration, but I don't get a sense of texture/feel from the descriptions up there.

Mileage will vary but in most cases you can custom blend, some stuff doesn't play nice but a majority of urethane resins will...

You can take a regular hard plastic like grade urethane casting resin and mix in a urethane casting rubber... Infinite possibilities and feels...

As for the texture a lot of that can be done pre-molding... A high gloss wet sanded original part will yield high gloss smooth castings, but on the other hand if you mist the part with say a flat paint prior to molding the resulting parts will have a satin like feel to them and will have a dull surface when cast...

Exo, that's quite possibly the MOST helpful piece of advice I've ever gotten! Thank you so much. I definitely want a satin finish, but something that's something not as hard as the standard white resins. It also needs to be paintable. I will look at the urethane resins and rubbers and probably talk to someone at Smooth-On about this.

I'm very new to casting; I've only ever helped other people cast their stuff and never delved into the technical stuff behind it.

Thanks, guys.

 

[Rocker]

BITY mold supply posts many videos on youtube that show different applications and materials. Follow this link and then check out their channel with links to their online store. YouTube - Mold Making: Basic Block Silicone Mold

 

[Ozymandius]

Mind if I piggy-back on this thread?

I've been wondering what kind of resin to use to get a slightly rubbery kid's toy feel to an item, if you guys know what I mean.
I read about hardness but nothing really describes texture and feel that I've found.

Smooth-On's Task 11, 13, and 14 is probably what you are looking for. It cures to a stiff plastic that's slightly rubbery and will flex and bend a small amount. Very much like a stiff vinyl feel to it.

They used to sell it as a semi-rigid plastic, but now rebranded it as one of the Task plastics. Pretty good stuff that cures with pretty much no bubbles.

 

[8 perf]

The Smooth-on site also has some video tutorials and LOADS of info on all of their products. Their customer service is great about answering questions too.

 

[modelnutz]

Smooth-On will also send small cured samples if you ask nicely.

 

[Organic Mechanic]

Smooth-On will also send small cured samples if you ask nicely.

Now THAT is a valuable service!