Epoxy won't stick to fiberglass in bilge

[TBarCYa]

I'm trying to epoxy a PVC ring to the bilge of my 08 Maxum and after several attempts I'm about ready to give up. The most recent adventure involved sanding thru what appeared to be paint to get to the fiberglass and then using a quick setting epoxy (5 minute general use good for fiberglass and plastics type) and letting it cure for 24 hours. Once cured, I siliconed the inside of the joint, put some light oil in the ring and then the transducer. Everything was great the first 2 times out but she sat for a week and when I took her out yesterday, the ring was not secured to the hull and the epoxy was stuck to the ring.

This is my 4th attempt at getting this thing to stick so if anyone has a suggestion for how to make my 5th attempt more successful, definitely let me know.

Thanks.

 

[Driven1]

Re: Epoxy won't stick to fiberglass in bilge

I believe the problem you're having is because epoxy and poly resins don't stick to pvc well. Try a polyurethane adhesive like PL Premium Construction Adhesive. Read the label and make sure it states that it will stick to PVC.

 

[ebry710]

Re: Epoxy won't stick to fiberglass in bilge

I'm trying to epoxy a PVC ring to the bilge of my 08 Maxum and after several attempts I'm about ready to give up. The most recent adventure involved sanding thru what appeared to be paint to get to the fiberglass and then using a quick setting epoxy (5 minute general use good for fiberglass and plastics type) and letting it cure for 24 hours. Once cured, I siliconed the inside of the joint, put some light oil in the ring and then the transducer. Everything was great the first 2 times out but she sat for a week and when I took her out yesterday, the ring was not secured to the hull and the epoxy was stuck to the ring.

Why can't you attach the ring to the hull with a bead of caulk and draw it to the hull with ss screws?

 

[TBarCYa]

Re: Epoxy won't stick to fiberglass in bilge

Driven1, the epoxy is holding to the PVC but not the bilge. In fact, I have to take it to the grinder to remove the epoxy for the next attempt.

Ebry, I'm considering that but I'm trying to avoid drilling holes in wet areas of the boat.

I think the next attempt may be to take a sanding disk or wire wheel to the bilge and make sure I can get it clean and rough for the epoxy to stick. If that doesn't work, it'll probably be caulk and screws in the bilge. I definitely don't want to drill holes in the transom.

Thanks.

 

[ondarvr]

Re: Epoxy won't stick to fiberglass in bilge

The problem may be from contamination on the surface of the bilge, there can be a great deal of oil, grease and other gunk down there. The area to be bonded needs to be thoroughly cleaned before you start sanding, sanding on oil just moves the oil around. Then get a small grinder, or plan on hand sanding a great deal to get down to a good surface. Also any silicone from previous attemps will keep the epoxy from sticking and silicone is much more difficult to remove than almost anything else so more work is needed to get a good surface to bond to. The next thing to try is a longer gel time epoxy, the longer it sit's on the surface before curing (to a point) typically the better the bond.

 

[Lone Duck]

Re: Epoxy won't stick to fiberglass in bilge

The problem may be from contimination on the surface of the bilge, there can be a great deal of oil, grease and other gunk down there. The area to be bonded needs to be thoroughly cleaned before you start sanding, sanding on oil just moves the oil around. Then get a small grinder, or plan on hand sanding a great deal to get down to a good surface. Also any silicone from previous attemps will keep the epoxy from sticking and silicone is much more difficult to remove than almost anythings else so more worrk is needed to get a good surface to bond to. The next thing to try is a longer gel time epoxy, the longer it sit's on the surface before curing (to a point) typically the better the bond.

After all the sanding is done, and you think it is clean of crap. Clean it again with( acetone) then when you are ready to install ring acetone again let dry and attach ring immediately.

 

[TBarCYa]

Re: Epoxy won't stick to fiberglass in bilge

I did clean it with acetone but since some of the area was still white while some of it showed the clear glass beneath, I'm guessing that's part of the problem. Next time around (after the rain stops) I'll get out the sanding disks and try to get the whole area down to clean glass and roughen it with some course paper to give the epoxy something to bite into. I'll try the longer curing epoxy too.

Thanks.

 

[TBarCYa]

Re: Epoxy won't stick to fiberglass in bilge

Looks interesting. I will probably give it (or something similar) a try because it will help assure a leak-free joint. Regular epoxy can run out and leave leaks that need to be siliconed.

Thanks.

 

[ondarvr]

Re: Epoxy won't stick to fiberglass in bilge

Acetone isn't a very good cleaner when it come to oil and grease, so that may be part of the problem. I wouldn't use silicone to seal it, if your having problems with it leaking pour some epoxy it the bottom of the ring, this will level it out and seal any small gaps.

 

[xxxflhrci]

Re: Epoxy won't stick to fiberglass in bilge

My bilge had 23 years worth of oil change spills in it. A couple of weeks ago, I mounted an in hull transducer. I cleaned the bilge with Simple Green and then cleaned the spot the puck was going with brake cleaner. The expoxy stuck tight. My unit works better glued in place than it did when I had water in the bilge and was trying to find a good place to put the puck.

 

[Coors]

Re: Epoxy won't stick to fiberglass in bilge

When you said 5 minute epoxy, is that hardware store?
You need real epoxy.

 

[jonesg]

Re: Epoxy won't stick to fiberglass in bilge

When you said 5 minute epoxy, is that hardware store?
You need real epoxy.

ditto, toy glue 5 minute epoxy is no good , it will not bond to poly resin.
I'm told it has too much wax.

slow 4 hr (worktime) 24 hr full cure epoxy works good .

 

[ondarvr]

Re: Epoxy won't stick to fiberglass in bilge

It sticks to polyester just fine and theres no wax in it, the same product with a longer gel time will normally bond better than it's faster version. I'm not saying the hardware store stuff is great and if you can get a small amount of quality stuff it will work better, but even the stuff you're using should work for a low stress item like this. The only reason for it to fall off would be a contaminated surface, or a great deal of flex in that portion of the hull.

 

[TBarCYa]

Re: Epoxy won't stick to fiberglass in bilge

Acetone isn't a very good cleaner when it come to oil and grease, so that may be part of the problem. I wouldn't use silicone to seal it, if your having problems with it leaking pour some epoxy it the bottom of the ring, this will level it out and seal any small gaps.

I would pour epoxy in the ring but if I end up with air bubbles in the epoxy the transducer won't work. This is the same reason I haven't just epoxied the transducer to the hull. I'm afraid that if I do this and there are air bubbles that there will be no way to recover and I'll have to buy a new transducer.

I have some West epoxy left from an old project but it's 3 years old. I also have some of the grey MarineTex I can try that appears (at least from the mix ratio) to be epoxy based. Would the MT be suitable for this type of project or should I buy a small amount of epoxy?

I guess my next steps are a good cleaner/degreaser, power sand until I'm sure all of the paint is gone, cleaner again then acetone and a good epoxy. I'll give it a try today.

 

[jonesg]

Re: Epoxy won't stick to fiberglass in bilge

It sticks to polyester just fine and theres no wax in it, the same product with a longer gel time will normally bond better than it's faster version. I'm not saying the hardware store stuff is great and if you can get a small amount of quality stuff it will work better, but even the stuff you're using should work for a low stress item like this. The only reason for it to fall off would be a contaminated surface, or a great deal of flex in that portion of the hull.

5 minute epoxy will not effectively bond to poly, thats a fact.

 

[TBarCYa]

Re: Epoxy won't stick to fiberglass in bilge

So far, I've gotten it very clean and used a 3m disc to remove the paint from the glass and had a good clean surface to epoxy the ring to. I then mixed a small batch of West epoxy and applied it to the whole area I cleaned plus the bottom edge of the ring and applied the ring. After about 5 hours I went back and mixed another batch but this time thickened it with wood flour and applied it to the inside and outside of the joint to ensure a good seal. Hopefully, by tomorrow morning it will be set up and ready to test if it's sealed properly.

The failed epoxy attempts involved applying the epoxy just to the ring but this time I figured I'd cover the whole area to provide more surface for the epoxy to adhere to. I just hope that it doesn't develop air bubbles that stop the transducer from reading.

Since the epoxy is old, I mixed a small test batch of the west epoxy to see if it would kick which it did so I'm hoping that it's still good. If not, I'll try again next week...

 

[TBarCYa]

Re: Epoxy won't stick to fiberglass in bilge

It looks like this attempt has worked. In the past, it would stick for the first trip out but would be unstuck the following weekend. I had thought that the bilge was white fiberglass but it appears to have been paint which I guess was causing the adhesion problems. The old West epoxy worked great and so far so good on the transducer.

Thanks for the advice guys!!

 

[Tim Frank]

Re: Epoxy won't stick to fiberglass in bilge

I have used 5 year old West resin with good results, but have found that the hardener is really iffy once you get past 12-18 months. The "browner" it has turned, the less likely it is to be useable.

 

[TBarCYa]

Re: Epoxy won't stick to fiberglass in bilge

Mine was a little brown but seems to have worked. So far, so good.