Smush Casting How-To

[Brett Barrow]

Here's a little how-to on what I call "smush casting". All you need to do it is some epoxy putty (any brand will do, I used Magic Sculpt just because it was the first one I grabbed, Miliput, Apoxie Sculpt, Green Stuff/Duro, etc... will all work just as well), a candle, and some sprue.

Here's what I'll be copying - the window cranks and door handles on this interior panel. I'm converting Revell's 1957 Chevy Bel Air sedan to a lower-model 210. 210's had a different interior trim pattern than the Bel Air, so I'll need to sand the panel flat and re-do it. I will want to replace the window cranks, door handles and armrests down the line and I'm not sure I'll be able to save them when I remove them from the panel, so I'll make copies of them so I'll have some spares.

I mix up a good blob of the epoxy putty and "smush" it over the detail I want to copy. I use a little saliva as a mold release EEEEEWWWWWWW! I let the putty set up fully before removing it from the panel.

And here's the result - A perfect negative mold!! Well, that's the idea anyway, one crank didn't come out quite right, I think there was a hardened chunk in the putty that prevented it from surrounding the detail completely.

Next, I take a long piece of sprue and heat it over a candle flame until it forms a blob, or "mushroom" on the end. Then, working quickly, I "smush" it straight down into the mold into whichever detail I want to copy. If I did it right, and I'm lucky, I'll get a perfect copy of the detail. This one wasn't perfect, but it was the best I got tonight because I couldn't get the candle flame to stay still because the A/C was blowing it all around. I'll try again when the A/C is off and I should get some better copies. I just wanted to throw this little how-to together tonight because I had mentioned it in a couple different posts and wanted to show how it's done. I'll trim the crank off the blob of sprue with a very sharp blade, like a scalpel or razor blade, X-actos won't usually cut it, if you'll pardon the pun, you need something sharper.

Well, there you go, feel free to use it if you need it, it can come in handy not only for interior details like this, but for exterior items like scripts and badges, and it really shines for making small bolts and rivets to add detail to plain parts or to replace detail that was lost when sanding seams or mold lines. I can't remember where or from whom I learned how do do this, it's been in my repertoire for years, but I didn't invent it, that's for sure.

[Darren B]

Awesome tutorial, thank you very much for sharing that will come in handy and a lot of builds I have lined up.

[crazyjim]

Brett, I've read of people keeping small pieces of cutoff sprue in a bottle of Tenax. The plastic supposedly just melts. Might it be easier to pour some melted sprue into the mold? Maybe not as much trimming.

[george 53]

Yeah, Jim I use sprue melted in Testors liquid cement for things like this, But you still have to wait for the"Goop" to dry in the mold. THIS sounds like a MUCH faster way! Thanks Brett, this is a REALLY cool idea!

[george 53]

Wouldn't silly putty be too soft? Does it harden if you leave it out of it's egg? I thought it would just evaporate. Still seems too soft to push an impression into it. But hey that's just my op.

[Eric Stone]

I think Silly Putty would be way too soft for this, but I wonder how Sculpey would work...

[george 53]

Personally Eric, I think THAT would hit it right on tha head!!!

[Eric Stone]

Doesn't Sculpey shrink when you let it dry/bake it? The Epoxy putty mentioned in the original post sounds like a better bet to me...it doesn't shirnk as it cures.

Yeah, it probably shrinks. Plus the Sculpey could distort as you remove it from the part to be copied. Guess we shouldn't mess with Brett's methods, as it looks like he's given us the right stuff to use from the start.

[Draggon]

Warning about Sculpey! It will melt into the plastic! I used some on an engine block to hold the intake in place for mock up and it softened up the plastic and ruined the block and the intake. Its been a year or so now, and the block is still sort of smooshy where the sculpey was.

[Agent G]

Sculpey contains plastisizers similar to the vinylizers in old kit tires. It will attack styrene like Godzilla attacks Tokyo.

Once baked it changes chemically and is relatively inert. I have painted it after baking but only with acrylics.

Two part epoxy putties are the best for this method by far.

G

[Brett Barrow]

I picked up some FIMO (similar stuff to Sculpey) today, I'm gonna try out some alternatives to the epoxy putty/styrene method, I'll post the results. I think it may be better for the larger parts when I can't get the hot styrene to fill the mold completely.

[wisdonm]

I have been using plumber's epoxy for quite awhile now. I get it at home improvement centers. It's about $6 for a stick almost 8" long. It is two parts, but one is inside the other. Just cut off a chunk, knead it up, in about 30 minutes it's as hard as a rock. I've used it to glue things together, make molds, fill gaps, make spoilers and wheel flares, as body putty, and to plug a hole in my sister's car's oil pan.

[randx0]

I was thinking the same thing. I was also thinking that Silly Putty might work just as well for making the molds ...

Not scoffing at your technique by any, means, Brett. Just kind of brainstorming on some other possible means of de-furring this particular feline ...

silly putty doesn't hold it's shape very long so it isn't good for making molds.

[highway]

Brett, have you tried this on larger items such as maybe wheels, grilles, or engine blocks? Also, have you tried it with regular resin? I have a couple projects stalled because I want a certain wheel or something, but I don't have any regular mold rubber and really don't want to waste the mold rubber even if I did have it. I've got plenty of quick set Alumilite resin, though!

Also, can any of the products you mentioned be found at Michael's?

[Brett Barrow]

Brett, have you tried this on larger items such as maybe wheels, grilles, or engine blocks? Also, have you tried it with regular resin? I have a couple projects stalled because I want a certain wheel or something, but I don't have any regular mold rubber and really don't want to waste the mold rubber even if I did have it. I've got plenty of quick set Alumilite resin, though!

Also, can any of the products you mentioned be found at Michael's?

No, I've never made any large parts with this technique. I have seen a product at Michael's that you could make larger resin molds from, it was a two-part silicone putty, I forget what section it was in, might have even been in the cake decorating section as they use it for making candy molds. You can see a similar product in the YouTube video* I posted about a while back, though the modeler uses molten solder to mold the parts, the technique would be the same with resin. I'm not sure resin would release from my epoxy putty molds, as there's no way to flex them, they're completely rigid. You can use another batch of epoxy putty to make the parts, it'll usually pop free. You can get a type of plumber's repair epoxy putty at Home Depot or Lowe's if you can't find the hobby-oriented brands I mentioned.

* link http://www.modelcarsmag.com/forums/index.php?showtopic=33454&st=0&p=337142&fromsearch=1&#entry337142

[highway]

No, I've never made any large parts with this technique. I have seen a product at Michael's that you could make larger resin molds from, it was a two-part silicone putty, I forget what section it was in, might have even been in the cake decorating section as they use it for making candy molds. You can see a similar product in the YouTube video* I posted about a while back, though the modeler uses molten solder to mold the parts, the technique would be the same with resin. I'm not sure resin would release from my epoxy putty molds, as there's no way to flex them, they're completely rigid. You can use another batch of epoxy putty to make the parts, it'll usually pop free. You can get a type of plumber's repair epoxy putty at Home Depot or Lowe's if you can't find the hobby-oriented brands I mentioned.

* link http://www.modelcarsmag.com/forums/index.php?showtopic=33454&st=0&p=337142&fromsearch=1&#entry337142

Thanks for the info, Brett, and I'll see if I can find the two part silicone the next time I'm at Michael's. All I've seen before is the one part brush one stuff in the same aisle as the glues, but I never thought about the cake decorating section.