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Anyone recommend a good adhesive that is safe for fiberglass. Would like to mount wood pieces to my high top so I can insulate in between and have something to screw into for the paneling over the insulation.

Thanks!
Check into Sikaflex products for this. highly respected in the boating world. not sure which of their products would be best for this intended application

Sometimes it is hard to get things to stick to fiberglass. While the inside of the roof should be the inside of the mold, and have no leftover mold release agents, who knows what might have accumulated on that surface since it was pulled from the mold.

A scotch brite pad in one gloved hand, backed with a few paper towels saturated with acetone, and clean paper towels in the other hand can prep fiberglass for secondary bonding. Just do not leave the acetone in continuous contact with the fiberglass. it evaporates quickly so one needs to lift any contamination with the clean paper towels within a second of wiping with the scotchbrite pad or similar. nitrile or latex gloves are not the best for this task as they will last only a minute or two before shredding. Get the thicker dishwashing gloves.

Secondary bonding issues are always a nightmare, so properly prepping the surface can save a lot of cursing later. With the different expansion and contraction rates of wood and fiberglass , the adhesive bond is very important, making surface prep just as important as the product chosen for it.

It could be a good idea to seal the wood on the fiberglass side too, with a polyurethane, and it is usually beneficial to thin the first layer of polyurethane with appropriate thinner, on application to fresh wood so it can penetrate deeper and seal better and be harder and stronger
Dry wood might absorb the good stuff in a sikaflex type product causing the bond to fail, and the polyurethane will prevent this, and will reduce the chances for moisture to contribute to lots of expansion and contraction which will work to break the adhesive bond.
(05-21-2016, 12:54 PM)SternWake Wrote: [ -> ]Check into Sikaflex products for this. highly respected in the boating world.  not sure which of their products would be best for this intended application

Sometimes it is hard to get things to stick to  fiberglass.  While the inside of the roof should be the inside of the mold, and have no leftover mold release agents, who knows what might have accumulated on that surface since it was pulled from the mold.

A scotch brite pad in one gloved hand, backed with a few paper towels saturated with acetone, and clean paper towels in the other hand can prep fiberglass for secondary bonding.  Just do not leave the acetone in continuous contact with the fiberglass.  it evaporates quickly so one needs to lift any contamination with the clean paper towels within a second of wiping with the scotchbrite pad or similar.  nitrile or latex gloves are not the best for this task as they will last only a minute or two before shredding. Get the thicker dishwashing gloves.

Secondary bonding issues are always a  nightmare, so properly prepping the surface can save a lot of cursing later.  With the different expansion and contraction rates  of wood and fiberglass , the adhesive bond is very important, making surface prep just as important as the product chosen for it.

It could be a good idea to seal the wood on the fiberglass side too, with a polyurethane, and it is usually beneficial to thin the first layer of polyurethane  with appropriate thinner, on application to fresh  wood so it can penetrate deeper and seal better and be harder and stronger
 Dry wood might absorb the good stuff in a sikaflex type product  causing the bond to fail, and the polyurethane will prevent this, and will reduce the chances for moisture to contribute to lots of expansion and contraction which will work to break the adhesive bond.

I'm currently doing something similar , on mine theres already plywood inside the fiberglass In some locations , I'm mounting my headliner to that plywood with a thin sheet of insulation behind it
3M   5200 adhesive silicon in tubes.
Thanks for the feedback. I appreciate it!
I second the 3M 5200. stuff is awesome. don't know if it's the right product for your application but it's one hell of a adhesive. it's considered permanent and is water proof. I used some over a month ago and my dog got some on him, it's still there. highdesertranger
I used E-6000 to attach PVC boards to my fiberglass high top. I don't think they'll ever come off.
I have been an E6000 user for years! It will basically glue anything to anything: wood to plastic; metal to glass; etc, etc. With the consistency of tooth paste it can also fill minor voids and fill-in when needed. It doesn't try very fast so it gives you a chance to carefully align the parts for a perfect. In a few days; the parts are almost impossible to get apart.

About the only application I don't use it for is gluing wood to wood; good old Elmer's; or Gorilla glue, is best for that.
(05-25-2016, 11:26 AM)speedhighway46 Wrote: [ -> ]I have been an E6000 user for years! It will basically glue anything to anything: wood to plastic; metal to glass; etc, etc. With the consistency of tooth paste it can also fill minor voids and fill-in when needed. It doesn't try very fast so it gives you a chance to carefully align the parts for a perfect. In a few days; the parts are almost impossible to get apart.

About the only application I don't use it for is gluing wood to wood; good old Elmer's; or Gorilla glue, is best for that.

Another E-6000 fan! Good to hear. I especially like it for when one surface is semi flexible. I've used it for gluing metal to rubber and it never came apart. For something totally rigid I would generally use epoxy. Between Gorilla glue, E-6000, and epoxy, if you can't glue it you might be doing it wrong.
3m 5200 is meant for through hull fittings on boats.  Very aggressive adhesive, and slow drying.  They have a faster cure version whose speed was not so impresssive either.  It requires humidity to dry.  One only has about a week to use up a tube once it is opened, but one can close it seal it,ziplock baggie it, and stick it in the fridge for more time.


I have also removed 5200, and found it easier to remove than expected, thankfully.  This was in roof gutter rust applications where I used aluminum C channel to rebuild parts of the gutter.  the 5200 cracked and allowed water in and the festering to continue.  Now epoxy saturated fiberglass is bridging that properly etched/scratched degreased steel aluminum gap with no signs of failure/stress.

I really like 'amazing goop' which might be similar to the e6000 which I have not worked with.

I Use the amazing goop in a lot of places as it is dielectric.  No worries about it transferring juice between + and -.

It dries nice and clear but stinks for a while after hardening, that toluene toxic cancerous smell.

When I worked in a boatyard, Sikaflex was the adhesive sealant of choice in wood to fiberglass bonding where polyester resin was not used, but I forget the exact sikaflex product.  It remained more flexible than 3m 5200.  The 5200 was only used on through hull fittings for below the waterline applications, and Sikaflex used on all through hull fittings above the waterline and the owners of the boatyard were very adamant about the Sikaflex use mostly everywhere but for below the waterline stuff where it was 5200 only.

Proper surface prep is key to a good bond whatever product is chosen for this application.

In terms of other glues for wood to wood applications, I much prefer Titebond 2 or 3  or other yellow wood glues, over Gorilla glue, unless there are larger voids to fill, and the expanding glue leaking from the glue joint is of no consequence to final product.

I feel the yellow glue can penetrate deeper into the wood for a stronger bond.  One can also mix a little water into yellow wood glue to thin it out even more so it can get sucked into the end grain of wood and really increase bond strength when cured.

Getting Gorilla Glue or other similar polyurethane type glues one one's fingers for any amount of time will turn them black, and a Pumice stone is basically the only way to return them to normal color.  Titebond glues are non toxic.

The best glue for bond strength is epoxy.  It is so aggressive it can even try to bond to waxed glass.  I've a few projects where waxed glass was used intentionally for allowing removal of project and I could not get the bond to break without heating and cooling the glass repeatedly  while working razor blades under the edges.

A problem with epoxy is many polyurethane type adhesives will not bond to it, and some will not cure when in contact with epoxy, but there are a bunch of asterix's involved in this blanket statement so do not chisel it in stone.
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