Resin Quality?

[thd9791]

Heyloo

Is there any way to tell the quality of resin castings from pictures? Lets say, hypothetically, there were blaster parts on some auction site cast in white resin, and the parts were really shiny and pitted/corroded looking.

Do bubbles/pitted surface just mean a bad mold? or does that suggest a light/bad quality resin?

I'd also like to know for reference in general, Good stuff to know

Thank you prop makers!

 

[TheAdama]

I'm still pretty new to the process, but I've been learning a lot about resin lately from attempting to cast something. I've observed a few things that could cause what you are describing. One possibility is bubbles in the resin from mixing. The cheaper resin I had was quite viscous, so after mixing it, I was left with TONS of tiny bubbles in the mix. Depending on how it was mixed(hand vs power tool), the number of bubbles generated could vary substantially. Pros use a vacuum rig to remove these. So, if that's what's causing it, yes it may indicate a cheaper quality of resin.

I've since moved on to a higher quality resin, which is far less viscous, and specifically states that it minimizes air bubbles, but if you took a squirrel mixer to it, and immediately poured it into a mold, I suspect you'd still end up with some if you didn't have the proper venting for your mold. So, I would say that it isn't necessarily an indicator of the quality of the resin or mold, but a sign of impatience/lack of thoroughness on the part of the caster if he isn't taking air bubbles into account.

Also, I would just flat out ask the seller. If they can't name the brand of resin they are using, I would be pretty surprised.

 

[loly2kn2]

I've used all sorts of resins and never really had a problem. I think it's more to do with the way you pour it. If you just slap it all in there you will get a bad casting. If you take it nice and slow and always think about where you are pouring and how the air can escape the mould then there shouldn't be a problem with bubbles.

also, IMO, if a seller doesn't even take the care to get a good casting on their own stock photos, imagine the amount of care they will take with customer orders.

Hope this helps you!

Lawrence

 

[MattMunson]

slinging resin is 95% technique, in my opinion. If someone is using a low grade resin, but has great technique, they will output a good part. The part might shrink, be brittle, or weep over time, but you can get great castings with bad resin.

The opposite is true also. The best resin in the world, in the hands of a lunatic, will yield bad parts.

It's often hard to tell if the flaws originate in the mold, the original part, or the cast part. But someone who knows what they are doing, and takes their time, can produce good parts regardless of the resin.

This kind of makes me want to do a tutorial on pouring resin!!!

 

[Matsuo]

A shiny casting usually, (but not always) means the molds are going bad and the maker has to inundate the mold with release agent in order to continue using it. This in turn will translate into problems for you the builder as you will have to spend an inordanate amount of time prepping the resin to get the paint to stick.

I do agree that bad castings are more the fault of the one doing the casting, than the resin. To wit if a supposedly good craftsman is using poor quality resin... He's not such a good craftsman. In the end it is entirely up to them weather they send said poor castings to a customer.

M

 

[toxicvenom]

The only thing you cant tell is if the caster has put excess fillers in the resin
to get more casts for the amount of resin they have, when I mean fillers they
will put anything in , the right stuff works Ok in the correct proportions I have
seen parts that look great .......then you have an accident drop or knock it and it shatters in pieces....

 

[TK7713Gra30]

If the rubber has not been degassed properly around the master, this will cause bubbles that will be replicated on every subsequent cast, rather than holes you will probably see the little beads of resin on the casting.

if the mould is good, but the casting has air bubbles, generally this means the resin hasn't been deggassed when being cast.

shiny does not mean bad resin, if the master is shiny, say a metal piece, the finish will be replicated on each cast.
that said, early castings can be shiny due to the catalyst still bring in the rubber, it takes a few casts to remove this.

with modern rubbers you don't always need a release agent, I get 30-40 high detailed polyurethane casts, figure, with undercuts and no release agent.