Rondo?

[superfunk]

So I've searched the forums on various sites and I just can't really find what the hell rondo is exactly composed of. I know the smartass answer would be resin and bondo...but I need more than that. I read that it's a 1:1 ratio and everything but do you add the hardener to both? How much working time do you have before it gets gooey? I would assume that its the same time as you would have with normal bondo..but it would be cool to have this confirmed before I waste a little bit of bondo and ruin my armor. So if anybody's got any helpful hints on rondo techniques, that would be most appreciated! I'm trying to finish the legs on my war machine armor and I just came across something about rondo and would like to use it if it works better than traditional fiberglass cloth.

Thanks in advance

 

[Risu]

Rondo is 1:1 resin and bondo with no hardener mixed together, then you add in twice the amount of resin hardener as you'd put in for the 1 part resin. Mix it really fast and pour immediately, it gets scalding hot and hardens within a minute or two.

 

[superfunk]

About how long is the cure time? Same as resin or bondo?

 

[Finhead]

It's a made up word. It's basically a cheap gelcoat. You can mix it however you want both are polyester based. The more resin you use the harder the material is but the thinner it is as well. If you use the resin hardener the finished product remains tacky, if you use the filler hardener the surface will not be tacky but takes more time to dry. It is in no way even close to the strength of fiberglass matt and polyester resin.

 

[superfunk]

So it's used as a thicker base for bondo?

 

[Risu]

I personally use it to backfill armor/helmet pieces. I coat the outside of the pep model with a couple coats of resin, then pour rondo into the inside (no more than 1/8" thick). After I get full coverage I drop in some fiberglass cloth and pour another layer the same thickness on top of it. That method has made my pieces virtually indestructible.

I don't have any issues with the surface being tacky, at least not after a few hours.

 

[Zaxmon]

It all depends on what you are trying to accomplish with it. If you are just trying to make a thicker resin, then you should use fumed silica aka Cob-O-Sil MiaPoxy - Mia 63 Fumed Silica

It's WAY cheaper and stronger.

 

[CustomPropSculptorGuy]

I just mix in some ultracal and baby powder if I need a cheap gel coat. Just mix the powders in with the fiberglass resin, add some hardener, mix, paint on a few layers with 15mins. between each coat, and then back it with some fiberglass matting; let it dry, then sand and lay on a couple layers of fiberglass and I am good to go.

 

[superfunk]

Basically, rondo would be used as a secondary reinforcement. Not just straight on top of pepakura?

 

[Kommissar]

is rondo brittle?

 

[Risu]

Not at all.

 

[Kommissar]

what would be best to reinforce a mask of sheet styrene plastic.
rondo.
or fiberglass?

weight is an issue.

 

[Pilot]

Kommissar - you have to be *extremely* careful with the products you use on a styrene piece. Normal automotive type fiberglass resin, and Bondo as well, are both polyester-based materials. One of the byproducts of curing polyester is styrene, and it will quite literally melt any other styrene it comes in contact with.

Polyurethane resin, like Smooth-On's products, would be safe to use on styrene. You could easily use it in lieu of the automotive resin along with some glass cloth to reinforce your helmet.

 

[the_batdemon]

Rondo is 1:1 resin and bondo with no hardener mixed together, then you add in twice the amount of resin hardener as you'd put in for the 1 part resin. Mix it really fast and pour immediately, it gets scalding hot and hardens within a minute or two.

The formula I learned used appropriate amounts of both creme hardener and MEK to a 1:1 bondo/resin mix. Chemically, I doubt there's much difference, you'd just be using everything that comes in the kits.

 

[Risu]

The difference being ease of use I think. Just using liquid hardener is just about as easy as it gets. With the rondo mixture already made, the liquid hardener is really easy to stir in quickly, which is good when the cure time is so short.

 

[Kommissar]

Kommissar - you have to be *extremely* careful with the products you use on a styrene piece. Normal automotive type fiberglass resin, and Bondo as well, are both polyester-based materials. One of the byproducts of curing polyester is styrene, and it will quite literally melt any other styrene it comes in contact with.

Polyurethane resin, like Smooth-On's products, would be safe to use on styrene. You could easily use it in lieu of the automotive resin along with some glass cloth to reinforce your helmet.

i appreciate that advice alot.
thanks.

though i have all purpose bondo resin, not specifically the polyester based, which is specifically labeled on the can as such. would that still be bad?
i'm going to try a few tester pieces i think

 

[superfunk]

So, if after I rondo a piece, what if I want to put resin or fiberglass cloth over the rondo? What's the probability that it would stick and would that be recommended?

 

[Risu]

As long as you cover the cloth with more rondo or resin, it';ll stick just fine. Haven't tried bondo over rondo, but I'd assume it works.

 

[superfunk]

Would it add more strength or basically just brittle depth?

 

[Risu]

Not sure what "brittle depth" means, but yes it would add more strength.