How to fix delamination without removing exterior fiberglass panels

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drusher

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Joined
Mar 12, 2013
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20
I figured out how to fix delamination without removing exterior panels.  This will make any delam better and perhaps like new, unless the delam is serious.  On older RV's with rippled filon sides, it will probably look like new.  On newer RV's with flat shiny fiberglas it will probably won't look entirely flat, but it will sure look a lot better.  If your RV has composite plastic exterior, it might not work as well.  I tried doing this on an older Toyota with some sort of composite reinforced plastic siding -- it did look better but the doggone composite would not compress back fully into place.

What you need:
1. Quarts of slow-set epoxy See: http://www.systemthree.com/store/pc/SilverTip-Epoxy-c10.htm
2. Large-body syringes with smaller tip (drug store). Veterinarians have larger ones if the drug store does not.
3. Length of 1/4" OD vinyl tube (hardware store)
4. Plastic ribbed tees to connect tubing with.
5. Old glass jars, small to medium size
6. Hunks of 1/2" plywood of suitable size to cover the delam area(s)
7. Fat bubble pak (office supply store)
8. Staple gun
9. Popsicle sticks (craft store) or other small stirrer
10. Old vinyl reinforced tarp or plastic dropcloth you don't mind wasting
11. 2x4's in assorted lengths
12. Bungee cords, nice selection, fairly strong ones.
13. Several clean paint stirrer sticks
14. Throwaway rubber gloves
15. Lacquer thinner.
16. Paint thinner
17. Cardboard box cut up into about 18x24 pieces
18. Ductape, don't use the kind that gets really gummy in the heat and leaves a mess.
19. Old clothes and old shoes you don't care about
20. Coathangers -- the 1-piece wire metal style with thicker wire
21. Full roll of paper towels
22. A helper over the age of 12 who has strong arms.

Prep:

1. park the RV someplace where you can lean the 2x4's against the delaminated area and wedge them into firm ground or pavement while leaning against the RV.
2. Remove something to get access to behind the delam area.  The wainscotting strip or perhaps or roof strip can come off.  You might have to take a window out if there is no other way to get access to behind the delam area.
3. tape dropcloth sections below the gluing area and lay some under the RV so you don't end up with epoxy running down any exposed sides of your lovely RV or onto your lovely driveway.  Put weights on the dropcloth under the RV so it doesn't blow away or flip up.
4. Cut plywood to size if needed.  Staple bubble pak on one side of the plywood.  If the plywood is warped at all, put the bubble pack on the inside curve side.
5. Cut 2x4's if needed for proper length.  I screw shorter pieces together with deck screws to get the desired length.
6. Drill the plastic tees out so they have a larger inside diameter (so epoxy can flow thru them better)
7. Assemble your glue shooter:  Cut the tube long enough to get all the way into the delam area.  Push it on a syringe and put a tee on the other end.  Cut a coat hanger long enough to tape to the syringe and still support the tube all the way to the tee.
8. Temperature should be about 60-80 degrees, but not under 50 or over 95 (epoxy sets too fast when it is hot and won't set when it is cold).  Don't try this if it looks like it will rain.
9. If you have a large area that is delaminated, only do about 3'-4' at a time measured horizontally.  You can't do the gluing operation fast enough to do a larger area.

REHEARSAL BEFORE GLUING:

1. Have your helper hold the plywood against the side of the RV with the bubble pak facing the RV, while you get a couple of 2x4's wedged into place.  The 2x4's should be at a fairly steep angle, about 30-35 degrees arc off the side of the RV.  Use bungee cords around the 2x4 and hook them to the underside of the RV to form a clamp.  The tip of the 2x4 will push the plywood up against the side of the RV nicely.

2. You need to have an end of a 2x4 at about every 12"-15" of the plywood going both vertically and horizontally in a matrix.  Your first time around you need to get all the bungee cords in place so you know you have enough bungee cords.  In most cases it will take 3 sets of bungee cords per 2x4 to get it nice and tight.  You know it is tight when you push hard on the plywood and it does not move in.

2. Take it all apart, laying the 2x4 in order so you can put them back in the same places later.  Lay your bungee cords out so they are lined up and not hooked together in a mess.

3. Ductape 2 glass jars in the center of a piece of cardboard so it does not move around.  One of them gets filled part way with lacquer thinner, the other will be filled with as much epoxy as you need. 

GLUING:

1. NO SMOKING OR FIRE ANYWHERE NEAR YOUR WORK AREA

2. Put your gloves on, mix the epoxy.  Measure the hardener carefully.  I suggest using about 10% less hardener than suggested so the epoxy does not set quickly (when epoxy it in a jar it gets hot and sets up quickly).  You can put the epoxy in the fridge to cool if off if you are worried about it setting too fast.

3. Mix epoxy quickly and THOROUGLY.  From this point on, you are working against the clock so do not waste time.

4. Dip the tee end of your glue shooter into the epoxy and suck the thing full of epoxy.

5. Insert the tee into the delaminated area at the HIGHEST point and start shooting epoxy, moving the tee back and forth to distribute the epoxy.  You need to do this fairly quickly.  When you pull the glue shooter out to refill, your helper pushes on the side of the RV to flatten the glue out so it doesn't just run down inside the cavity.  If there is de-laminated plywood in there, squirt both sides of the plywood.   

6.  When you are refilling your glue shooter, your helper's job is to press hard several times in the area you just shot glue into to spread the glue around so it doesn't all run out.  Your helper keeps track of where you have already shot glue (using little pieces of tape stuck on the side), and then lifts the panel away from the side of the RV with paint stirrers so you can slide the glue shooter back in easily for the next squirt.

7. For some areas you might find it easier to dip a yardstick or paint stirrer into the epoxy and work it into the area.  I takes several tries with this approach to get enough in there.

8. Keep shooting glue in there until you start to see it running out at the bottom (if you are working in an area where that can happen)  WARNING: If there are hinges or locks under where you are shooting, be careful because the glue might come out at the hinge or into a lock).  If that might happen it is best to remove these items before shooting.

9. Rip your rubber gloves off. You do not want to get epoxy all over the RV.  Clean your hands off with lacquer thinner if you got any on your hands. Get the plywood sheet into position with a couple of 2x4's and bungee cords so the plywood stays in place.  Put the rest of the 2x4 in place with all the bungee cords.  Press on the plywood in various areas to make sure it is all snug against the side of the RV.

10. Clean out the syringe by dipping the tee into the lacquer thinner all the way up into the syringe body, and shooting it out again.  Do this several times.

11. If you got epoxy on anything your should not have, clean it off with paper towels and lacquer thinner.  The usual precautions about your RV paint and plastics apply.  You can use paint thinner instead but it takes more rubbing to get it all off.

12. Take the syringe plunger out of the syringe and wipe it clean with lacquer thinner.  Leave it out of the syringe.

13.  Let it set for at least 24 hours.  Save the glass jar you mixed the epoxy in so you can check it to see if that epoxy set.  If it is still sticky, do not take the clamping arrangement off until the epoxy in the cup is nice and hard.

By now, your neighbors probably think you have lost your marbles.  Who cares, go have a beer.

If you need to do another section, you might want to replace the plastic tee and tubing.  If they did not get fully cleaned out it will be much slower shooting glue the second time.







 
" By now, your neighbors probably think you have lost your marbles.  Who cares, go have a beer."

Your neighbors might think you're bracing for high winds.
 
Make sure not to get polyester resin as I'd think auto parts places have that as well.  Marine supply will have epoxy for sure.

I think the easiest way to tell is that epoxy is mixed 50/50 so you'll buy epoxy and hardener in equal amounts.  Polyester resin hardener comes in a very small bottle and you use very little.

and a HUGE thanks for drusher for the detailed write up!  I think this one belongs in the library.
 
The downside for polyester resin is that the fumes are not good to breathe.  The upside is that it's relatively cheap.  If you have to do this, consider West Systems epoxy resin.  It's not cheap, but with the pumps on the cans, mixing errors are unlikely.  Mix your epoxy wrong and you have a sticky mess instead of an adhesive.

http://www.westsystem.com/ss/
 
SubVet said:
The downside for polyester resin is that the fumes are not good to breathe.  The upside is that it's relatively cheap.  If you have to do this, consider West Systems epoxy resin.  It's not cheap, but with the pumps on the cans, mixing errors are unlikely.  Mix your epoxy wrong and you have a sticky mess instead of an adhesive.

http://www.westsystem.com/ss/
Polyester resins have a lot of downsides,  for more information: http://www.redrockstore.com/resin.htm

If you're going through the trouble to fix it, epoxy is the way to go.  I've built a few small boats with west systems and it's good stuff.  It may be expensive but I wouldn't think much would be required.
 
braindead said:
Make sure not to get polyester resin as I'd think auto parts places have that as well.  Marine supply will have epoxy for sure.

I think the easiest way to tell is that epoxy is mixed 50/50 so you'll buy epoxy and hardener in equal amounts.  Polyester resin hardener comes in a very small bottle and you use very little.

and a HUGE thanks for drusher for the detailed write up!  I think this one belongs in the library.
The only reason to "make sure" that one uses epoxy would be if the original panel is made using epoxy resin. Epoxy resin will adhere to polyester but polyester will NOT adhere to epoxy. It may be worthwhile checking with the manufacturer.

The description of this repair entails adhering 2 pieces of material. it does not entail wetting out cloth and one is not concerned about water penetration (like in a boat hull that is constantly immersed in water). There may be some slight benefit to using epoxy resin for this type of repair but I just don't see it unless the original material was epoxy resin.

Having said that, I doubt if the original panels are made using epoxy resin. The cost is prohibitive and there is little upside on an RV. Almost all production boats are also built with polyester resin as the cost is less than half.

A couple of tips when using either resin...... use the ratios that the manufacturer recommends...... you can buy slow curing resin. Messing with the design ratio of epoxy resin will change the finished product (usually making it brittle). Polyester resin is less demanding on the ratios.

When you mix 2- part resins, use the largest diameter, flat bottom, mixing bowl practical. As the OP mentioned, resins cure by heat (not evaporation). Spreading the surface of the mixed resin will greatly extend the working time as the exposure to air will release more heat and retard the curing time (although you may experience slightly more waste). IMO, this repair would best be done in temps below 70* and very low humidity....... NEVER pour resin after Sunset.

I've built a few F/G sailboats and repaired even more. Learned a lot of tricks of the trade.

couple more tips that just came to mind.....

When working with resins, wash your hands with liquid hand-soap (no water) and allow the soap to dry on your skin. While you are working, you won't even notice that it's there. When you are finished, wash your hands and everything will come right off. This works well for paint as well.

White vinegar makes a good cleaning agent for resins. It will clean your tools easier that thinners.
 
I stand corrected.  I had used system three epoxy with great results doing an old Winnie.  I used the stuff from the auto parts store on the toyota RV and it did not work as well. 

System Three Silver Tip epoxy is not cheap but it is real good stuff.  Get the slow-set hardener.  See: http://www.systemthree.com/store/pc/SilverTip-Epoxy-c10.htm

System Three also has materials for stopping wood rot.  I have found that the epoxy does a fantastic job stabilizing delaminated plywood behind the fiberglass that is dry and ready to fall apart.  It soaks into the plywood and makes it strong again. 

If the moderator could modify my original posting with this new information it would be great.
 
drusher said:
If the moderator could modify my original posting with this new information it would be great.
You can modify your own post if you'd like...... Just click on "Modify" in the upper right of your post.
 
I also used West Systems epoxies before some years ago.  It is good stuff but expensive.
 
Good article. The main criterion though for success must be accessibility from behind the delaminated area.  Our Winnie has a large bubble on the passenger side between the galley & bathroom windows - right behind the cupboards & appliances.  I'd love to address it, but for me, it's a non-starter for that reason. :(

Dougie.
 
Great write up on the repair.  Just a couple thoughts.  Epoxy resin is the only way to go.  It has much better adhesive properties than polyester resin though it does come at a cost.  If I were doing a repair I would follow your initial write up.  If there are bubbles in the side and no easy injecton site there are a couple options. If the bubble will push in flat(key point) you could drill a couple small holes to inject the epoxy and cover them with a pinstripe or anything else that fits, or you might be able to drill through the back of a cabinet or closet to inject from the inside.
One big item, if the area to be repaired has gotten wet it MUST be dried out or no resin will stick.  Some polyurethane adhesives(3M 5200 or equal) will work on damp surfaces but they are harder to get into small spaces.
 
braindead said:
Make sure not to get polyester resin as I'd think auto parts places have that as well.  Marine supply will have epoxy for sure.

I think the easiest way to tell is that epoxy is mixed 50/50 so you'll buy epoxy and hardener in equal amounts.  Polyester resin hardener comes in a very small bottle and you use very little.

and a HUGE thanks for drusher for the detailed write up!  I think this one belongs in the library.

Epoxy can be 50/50 but often is not. Two brands mentioned here, West and System Three are not 50/50, whatever used should be mixed exactly as specified.

Edit; Whatever product used reviewing the safety warnings is essential especially concerning fire since the method described involves working from inside the RV. Mixing the epoxy in a plastic container is a much better choice than a glass jar. As mentioned above a shallow flat container is best to slow down the heat build as is a small batch. In case your batch overheats the instruction to have the mixing container taped to a board will make it possible to get it out of the RV quickly. You won't be able, or want to touch it directly.

If the inside of the wall is wet it must be dried out completely first or this won't work.
 
I know this is an old thread but I am getting ready to try it on a small area that is non structural. Issue here was the large bubble wrap but ended up you could get a 2 foot by 7 foot piece of the large for 4 bucks and change at the local ups store. really wondering if Gorilla glue would be as good or better.


Garry
 
Gorilla Glue is a good adhesive but it expands considerably as it dries. If you're trying to repair a large delaminated area, you could end up with a glue bubble where the delamination was. Just something to think about if you want a smooth, flat finish.

Kev
 
gmfoster said:
I know this is an old thread but I am getting ready to try it on a small area that is non structural. Issue here was the large bubble wrap but ended up you could get a 2 foot by 7 foot piece of the large for 4 bucks and change at the local ups store. really wondering if Gorilla glue would be as good or better.


Garry
If Gorilla Glue is clamped very tightly, as not to allow any air to form in the joint, it works very well. For what you are doing, air will enter the glue as it cures and form expanding air bubbles. This "air bubble expansion" also weakens the Gorilla Glue by about 90%. You could end up with a real mess on your hands.
 

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