Slush Casting-- Has Anyone Tried it?

[Treadhead]

I've heard a lot about slush casting but have had limited results in doing it. Basically it involves pouring a small amout of resin in a mold and slushing it around until there is a fine coat of resin on the surface of the mold.

Subsequent layers of resin are added for thickness.

I sometimes wind up with uncured resin on the surface of the casting. Bubbles are sometimes an issue, but I can fill those as a last resort.

Anyone have any experience with this? Can anyone give me some pointers?

Thanks:)

[JimPV]

If the object your casting has several distinct sides, you could always pour in some resin, lay it on a side, let that cure and then repeat for each side. This will allow you to cast it hollow and still contol the thickness to some extent.

[Antenociti]

We do slush casting a fair bit with plaster items where it is very effective - of course its a lot more liquid than resin and you've more working time with it.

Never tried it with resin although we're getting in a 24 minute pot-life urethane resin soon and may try it with that.

[Sparky]

Almost missed this one, it is also called roto-casting, there is something called spin casting which is more for eleminating bubbles and casting fine details.

I bashed together an electric roto-caster and gave it a test a while ago. It's good to go. Needs a timer and regular power supply but it works.
http://www.kc6sye.com/techmages_3_27_06.html

I need to snap some more pics of it and try to get them pushed into the page and add it to the backup casting presentation. So much to do in 2 days!

[sillyface]

I've done a couple of head casts in that way.

What I do when I use resin is just use a little more catalyst as instructed and pour just enough of the mix in the mould to cover the inside surface. This will pick up every detail and produce little of no air bubbles and then slush it around.

Not too long after it has cured make up a second mix with the right amount of catalyst and do the same. This will set and stick with the first mix and give it structure.

[karim]

I like slush-casting, because its a pretty good way of getting good casts if you aren't invested in vacuum/pressure pots, and only want a couple of pulls

It's also a neat way to leave lighting space in the part.

I used it for the engines for my Moldy Crow scratch.

[modelnutz]

I might advise that you use a fairly fast setting resin such as Smooth-on's SC-300 or SC-320 ( or similar ).
I also find ( via roto-molding experience) that a bit of filler ( such as Smooth-on's Ure-fill )should be considered. This increases the thickness of the coating and reduces the chance of a mass curing and slumping inside your part, as well as reducing problems found on inner sharp corners.
Think of the flow thickness of honey ( filled resin ) as opposed to water (un-filled ). The un-filled will pick up details a bit better but will also run away from inner corners.
You may need to "pre-load" some areas of your mold before slushing ie. ears,noses etc. as the filler can prevent these areas from filling properly.
Or, you can just do a bunch of coats...just don't wait too long between coats. You want to lay down a new layer as soon as the previous layer kicks.

Sorry for the ramble....hope the info helps.
Good luck and be sure to let us know how it works for ya' !

Modelnutz 8)
no, I do not work for Smooth-On

[Stu Pidasso]

The above posters mentioned doing multiple layers. How is this accomplished? My thought is that if you put resin in a mold, slush it, there will be a solid shell coming out of whatever you cast. Then how do you do a second coat on the inside without ruining the detailed exterior of the cast?

[modelnutz]

The above posters mentioned doing multiple layers. How is this accomplished? My thought is that if you put resin in a mold, slush it, there will be a solid shell coming out of whatever you cast. Then how do you do a second coat on the inside without ruining the detailed exterior of the cast?

Jimi, it's pretty simple actually.
What I do is slide a short length of silicone tube ( or a drinking straw from MickyD's) into the pour hole.
The tube should be a good snug fit and should extend in to the mold about an inch or two so that the resin in the mold will not leak out when tumbled.
When the resin cures, it's a simple matter to pull the tube out of the mold and Ta-Da ! You still have a pour hole for subsequent pours.

This technique also allows the mold to "breath".
Remember...resin gets hot when it cures....if you did not vent the mold, the air would have no way to escape and would therefore expand
( inflate might be a better word for it ) the part being cast.

Lots of words there for a pretty simple concept....sorry for the ramble.

YodaNutz

[Ti Raven]

Cool technique, thanks!

[modelnutz]

Cool technique, thanks!

You're more than welcome

[Stu Pidasso]

I've been slushcasting these... Basically I've been pouring some resin in the mold, closing it up, and turning the whole mold SLOWLYaround in my hands like a Rubik's cube. I have to do this until I have the time to build my own rotocaster. Side view.