glassing over stryofoam

Latex is soluble in styrene. I don't think it will work.

 

Is there a way to use styrofoam as the mold for a sealed space and then dissolve/drain the styrofoam out to reduce weight?

Is there a structural advantage to then filling the cavity with pressurized air and sealing it? Ie, like a inflatable but with hard materials.

 

It would be a very complicated technology. The Saturn V rockets were kept rigid with fuel pressure.

 

Are you saying to make sure all the styrofaom is covered even if using epoxy?

 

If you use epoxy there is no need to put anything on.

 

Evidently dissolving the styrofoam male mold is called "lost foam" construction and is in use. Sounds like a good technique when combined with a CNC router to create the mold.

 

What do you propose to do with the toxic waste?

 

Thanks Gonzo..what do you think of the suggestion to use plaster over the foam?

 

Use nothing over the foam!

The bond of epoxy to the foam is good to sufficient when the first layer of glass fabric is not too coarse. Say under 100gram m².

For such a small boat I would build a female mold. The weight of the foamcore and much more, the weight of the fairing putty to get a proper result, will make this a heavy boat.

When you just go for a sample your method is ok though.

And use the cheapest Epoxy resin you can find! Do´nt let them talk you into "quality" or "Marine grade" thats nonsense. The quality of ALL resins on the market is top.
Do not use a hardener with a too long pot life, they need a postcuring at high temperatures. A procedure Styrofoam does´nt like.
Do the layup in one go! That means, do not let one layer cure completely before you apply the next. That makes a much stronger structure and does never delaminate.

Take care!

Hoytedow said "I have heard", that does´nt mean much (sorry Hoyt).

Gonzo has done what he is talking about!

Rwatson seems to have understood a mold to be built. (where plaster is a common method in homebuilds)

jonr never knows what he is talking!

Regards
Richard

 

The only problem with epoxy, is if it has too high viscosity. However, with a light fabric it shouldn't be a problem

 

Let me get this straight . That foam that your Tv comes in will melt with polyester resin I know but your saying epoxy will not have such an effect?

 

Right.

 

polystyrene and epoxy

Yup.
http://www.youtube.com/watch?v=uaYtu17Xt_M

...and, as usual, RW is dead on. Vacume bagging and post cure is the ONLY way to go for glass over foam.

 

Well can't you thin it a bit with some acetone for the first coat till its firm enough to be rough handled?

 

Yes, acetone is a perfect solution.........

to get rid of the foam.

Never use thinner with epoxy! Ramp up the temperature instead, or get a thinner resin.