Glues for Foam on Fiberglass...?

Howdy,

I need to glue some closed cell foam to fiberglass. This is not for a boat, but is for a fiberglass fiddle case I just finished.

I know that contact cement would hold well, but because it can't be repositioned, it just will not work for me given the complex curves of the case.

What type of glue would be tacky enough to hold the foam in place initially, but would allow for some repositioning before setting up? Also, I want to spread, or brush it on, rather than using an aerosol.

Sincere thanks for any help on this,

A.C.

 

Velcro is the answer

Velcro pads? Just wet the case with contact cement, let it dry that it doesn't feel tacky when touched and then carefully position Velcro pads. Use contact cement from any hardware store and spread it with a brush made out of sheet of paper rolled in a tube and then flattened. That should do it.

 

Howdy,

The Velcro approach is something that I already use in the case, but not for the foam. The hitch is that the case conforms extremely well to the shape of the fiddle, and bow, so some of the foam padding is only 1/8", and with the Velcro, the fit would be too tight.

I did install the foam though...

I found a glue made by Loctite, and it becomes tacky rather quickly so that it holds the foam in position, but I can easily reposition the foam for about 15 minutes, so the fit is really good.

I thank you for your suggestion,

A.C.

 

vacuum infusion

Have you considered using vacuum infusion.
This technique would allow you to position, and reposition as much as you desire, under the vacuum pressure. Once you have the position that you want, then introduce the epoxy resin.

 

Howdy,

I've solved the specific problem, but am eager to understand more about your suggestion...

No doubt I am misunderstanding something, but would not introducing resin coat the foam, and by doing that defeat, the reason for having foam in the first place? I want to have the foam to absorb the energy of, for example, dropping the case.

Sincere thanks,

A.C.

 

You are correct that ordinarily VI is used for FRG to cover the foam, however, you may be able to alter the procedure to meet your needs.
I see two points of difficulty for your needs.
1) sealing the edges of the foam so that there are no leaks to the outside surfaces. This should be doable depending on the foam used and the sealant tape. There is a yellow malleable sealant tape commonly used in VI which would probably solve this problem.
2) the geometric configuration to allow the connections to the vacuum lines and resin lines. You would need to experiment a bit, but try the geometry with resin flowing in one edge and a vacuum pulled on the opposite edge. I'm visualizing a simple rectangle.
Also, resin typically flows through a flow media, which probably does not apply in your case. You will probably deliver the resin directly to edges which don't have vacuum applied to them. Glass cloth between the substrate and foam might provide the needed space for resin to flow. You need to experiment with types and thicknesses. I'd cut the glass slightly smaller than the foam, providing a gap around the edges of the foam.

 

Hi again,

As before, I have learned from your comments, and really thank you for that.

All the best,

A.C.