Smooth-Cast 300 vs ROTO

[becks]

Odd, I wasn't able to make any new threads in the noob section...so.
Looking at what I want to cast our helmet (see link in sig if you're not familiar with the project) out of and I came across a couple options.
Obviously the slush casting/rotocasting is the process that will be uses, however looking at Smooth-ons website today I noticed a Smooth-Cast ROTO exists in addition to the standard Smooth-Cast 300. It seems the ROTO is "less rigid" but Im curious to what extent. Does anyone have any experience with this ROTO product they sell? Pro's/Cons?
Thanks!

 

[Roadwarrior]

I've heard that Roto cast is heat sensitive and can warp, IE, if left in a hot car.

 

[becks]

Ah ha! Yes that would made quite a difference. Thanks for the info!

 

[Beau Nidle]

I used Roto, and switched to the 320. Roto is not rigid enough, and will deform under its own weight in certain cases. If you just want to make a MkVI helmet with it, it would probably be fine, but I would go with the 320 anyway. It slushes almost the same as the Roto and is much more rigid. Avoid 300 for slush casting, it sets up too abruptly, and you'll probably be left with lumps in your cast.

 

[Hickeydog]

I used Roto, and switched to the 320. Roto is not rigid enough, and will deform under its own weight in certain cases. If you just want to make a MkVI helmet with it, it would probably be fine, but I would go with the 320 anyway. It slushes almost the same as the Roto and is much more rigid. Avoid 300 for slush casting, it sets up too abruptly, and you'll probably be left with lumps in your cast.

Had the same experience. 300 gives you about 3 minutes from mix to stiff. 320 gets you about 10 minutes, which makes getting even coats on a large piece fairly easy.

 

[LMNOspartan]

Had the same experience. 300 gives you about 3 minutes from mix to stiff. 320 gets you about 10 minutes, which makes getting even coats on a large piece fairly easy.

oooo that makes sense thanks because i was wondering about those two too.

While this thread is here (i WAS gonna make my own in a few minutes but this seems like a better idea) i have a quick question regarding casting materials.

So i was browsing the smooth on site and i came across something called featherlite. It's a casting plastic that is supposed to be really light. I mean, it can float! Has anyone worked with this before? and if so how good is it?

oh and here's a link http://www.smooth-on.com/Urethane-Plastic-a/c5_1120_1162/index.html

 

[Beau Nidle]

Looking at the tech stuff, it seems fairly soft, even more so than the roto. It would probably be OK for fairly solid castings, but a helmet or armor, which can deform easily under the right conditions would probably not work well.

 

[LMNOspartan]

o

Looking at the tech stuff, it seems fairly soft, even more so than the roto. It would probably be OK for fairly solid castings, but a helmet or armor, which can deform easily under the right conditions would probably not work well.

oooo thanks. makes good sense. that decides it. thanks a lot!

 

[ShadoKat]

This is interesting... according to the product description, "Feather Lite is a heavily filled low-density urethane casting resin." And per the tech sheet, "Material is heavily filled and the filler will separate from the liquid during storage. When you first open containers, you will see powder on top that must be thoroughly pre-mixed with liquid on bottom." By "heavily filled" it sounds to me like they mean it's basically just one of their other casting resins that has microballoons pre-mixed into it. For the price, you might be better off buying the microballoons separately. Microballoons, if used excessively, can also make your casting extremely brittle, so by buying them separately, you can also control just how much to add.

On a side note, it's funny they'd say "heavily" filled while trying to emphasize how light it is

Had the same experience. 300 gives you about 3 minutes from mix to stiff. 320 gets you about 10 minutes, which makes getting even coats on a large piece fairly easy.

If you're slush casting by hand, though, and your mold is very heavy, keep in mind how long you'll want to be handling it. From my own experience, 320 takes about 15 minutes to set up enough to the point where you can put it down, and my arms are completely dead afterward. Also, I've found that as 320 begins to gel, I get pretty bad lumps anyway if I rotate the mold too slowly. Obviously I'm not expert, but I've found that I get much the same results with 300, which sets up in 5 minutes, but with far less fatigue.

 

[Hickeydog]

If you're slush casting by hand, though, and your mold is very heavy, keep in mind how long you'll want to be handling it. From my own experience, 320 takes about 15 minutes to set up enough to the point where you can put it down, and my arms are completely dead afterward. Also, I've found that as 320 begins to gel, I get pretty bad lumps anyway if I rotate the mold too slowly. Obviously I'm not expert, but I've found that I get much the same results with 300, which sets up in 5 minutes, but with far less fatigue.

Excellent point. I use Smooth Cast 320 to harden my pep work, instead of fiberglass, so the piece is very light to start with. I also need the extra working time to get the mix in place in the pep work. It's not quite as fast a mold.

For molding, I agree. The faster cure time of 300 would be a big benefit.