Foam plug- cycle fairing- question

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#1

I have this motorcycle fairing I made out of styrofoam and I’m trying to figure the best way to prep it for molding.

Here’s a pic of it in progress…

I’m kinda looking at several options but see limitations with each.

  1. Coat and glass with fiberglass cloth and epoxy.
    Problem: I’ve heard of problems with the fabric lifting and air pockets particularly with epoxy with complex shapes.
    Also, am not sure how to surface finish the plug. Can you use a styrene product like Duratec’s primer over epoxy??? Is there an equivalent epoxy surfacing resin?

  2. Coat and glass with fiberglass cloth and Styrosafe(a Duratec product made to use over foam). I could then confidently finish with Duratec’s primer and high gloss products.
    Problem: How much contraction and warpage do I have to worry about with maybe one or two layers of 6oz cloth? Does a single or a couple layers of 6oz cloth sound appropriate for this application?

  3. Coat with a foam coating. I’ve actually purchased a couple quarts of styropoxy, an epoxy hard coat for foam.
    Problem: Again, how to finish the plug to a high gloss? Are Duratec’s primer and finishing products compatible. Is the foam coat hard enough to take a mold off of?

How would you proceed? I’d like to keep the dimensions as close to current as possible. Which weight cloth or mat would you use?

Thanks!
John

#2

What is the product currently on the foam (yellow), Styrosafe? Also, how are the foam pieces held together?

The foam will be very dimensionally stable but as you suggest you need a very hard surface coat. I would personally sand the foam down an additional .050" or so and make sure there are no high spots. Next I would spray the plug with several coats of latex house paint. This will form the barrier for poly. Then I would use light CSM or a few coats of surfacing veil. There is no substitution for CSM and conformity to a surface. After this apply filler and coat with your Duratec. Be sure you don’t break the surface of the glass when sanding filler because you will loose your local strength and barrier coat, so plan to add rather than remove material.

My .02

#3

Elmer’s wood glue. :o The panels are glued with a styrofoam spray adhesive.

Thanks! If I use styrosafe, I could skip the latex paint stage right? Use styrosafe to wet out 1.5oz chopped mat over the foam. I have to look up what veil is?

The rear seat you just catch a glimpse of in the second pic, I did what you recommended with the latex house paint. Then I used bondo (premium brand :smiley: ) to smooth the surface. I left the seat cover in the sun one day and the paint bubbled off the foam and deformed the bondo. I agree with you I need a more durable surface.

#4

[QUOTE=jcw;25284]

Thanks! If I use styrosafe, I could skip the latex paint stage right? Use styrosafe to wet out 1.5oz chopped mat over the foam. I have to look up what veil is?
QUOTE]

Not sure, I say poly because it will dissolve the binder in CSM. Also, I would use a lighter CSM, 1.5 can get difficult. Veil is amazing it’s .010 or .020 thick and will conform extremely well. It looks like your shape is simple enough to deal with .75oz CSM.

#5

Great! Thanks.

I’ll contact duratec to see if styrosafe will wet out CSM. Although if it’s styrene that dissolves the binder in mat and sytrene that melts sytrofoam, my guess is that it might not work well with mat. :smiley:

#6

Styrosafe will not work with mat apparently.

The guys at expresscomposites recommended 6oz cloth and styrosafe should lay up for the plug just fine.

I’ve been searching this and other forums for tips and techniques for laying up cloth. I know it’s a very basic question, but I’m sure there’s a learning curve with it. Are there any tricks or things to watch out for. What I anticipate is that if I lay the cloth over the plug, it will bunch up in places and not lay flat. Right? Will wetting out the cloth flatten everything?