Fiberglass Fail, Backpad restoration goes bad... Options

[bigkensteele]

So I have this really nice tan interior that I am refurbishing. Like most, the bottom of the backpad needed some work, and I saw a thread a while back where someone here used fiberglass to fix the bottom edges. I decided to use the same approach.

I have been putting this off for a couple of months because it has been probably 25 years since I have done anything with FG, and that was the floor of my brother's boat. That was relatively easy because we just mixed up the whole can and tube of hardener and three of us brushed it out.

I decided on Sunday that I wasn't going to put it off any longer. I knew that this might not go well since it is hard to look into a cup of resin and determine how many drops of hardener to use. Well, I apparently didn't use enough. Two days later, there are spots that are still tacky, and the glass isn't adhering on my largest patch.

Any thoughts or recommendations are welcome.

This side turned out OK as it was in pretty good condition anyway. It has fully hardened.



This side, not so good. As you can see the glass is not sticking, and large areas are still tacky, especially underneath the spots that I had clamped with wax paper.

[SLITS]

heat gun?

heat lamp?

[Mike Bellis]

I would mix some resin extra hot and go over it again. If you had enough hardener, you could spray on the old mix and overlay a normal mix. Won't be perfect but should save the back panel.

[URY914]

Pull off the fabric and scrap off as much of the mix as possible.

Do it over.

[rick 918-S]

I'f it's not hard just pull it off and start over. Mix it hot and it will kick off any resin that has soaked into the backing.

[tracks914]

Peel off the glass and throw it away. Mix a batch of resin. Brush the new resin directly to the cardboard and work it into the old resin. You aren't looking for structural strength here just a stiffener. The resin that soaks into the cardboard will be more than enough to do this. Use a bit more hardener than usual and it should activate the existing resin.
BTW mix up both products well before using them. This will assure a better reaction.

[bigkensteele]

Thanks, fellas. I peeled off the glass and was able to get it off without too much damage. Not sure that I really need it, but the big patches were covering spots that were cracking and/or delaminating.

Any pointers on mixing to insure that I get the right ratio next time for the hot mix? Can I buy throw away mixing cups with volume marks.

FYI - FG resin will melt a Red Solo Cup. Toby Keith forgot to mention that.

[McMark]

Look at a paint store or the paint section for measure cups. Or grab a cheapie at Target.

[KELTY360]

Go to a thrift store and buy a cheap measuring cup.

[FourBlades]

Use waxed paper cups to mix it.

Like the old Dixie cups.

Don't use glass or plastic ( you know that).

I buy 25 packs at a grocery store in 12 ounce size for small jobs.

Use 10 drops of hardener per ounce of resin.

Once you have mixed and used a batch the cup is trash, but don't throw it away until you are sure it has cooled.

Using disposable cups makes it so much easier.

John

[effutuo101]

http://www.perryfiberglass.com/plastic_duc..._wet_screen.pdf

I found information like this helpful. Don't mix in high humidity or when it is going to rain.

Resin is cheap. Mix a batch and let it set. Some adjustments and you will be good.
I agree with the comments above. Mix a hot batch and it will activate with the extra on your back panel. Do this in small batches otherwise you will get 1/4 the way through when your glass snaps and hardens.

[76-914]

Years ago I found that some resin mixing directions refer to volumetric ounces whilst another was ounces of weight. I'm the guy that did that thread a few years ago. Take the glass up about 6" past the spot you want to repair and be sure to get a good soak into the cardboard backing before laying the glass. Avoid a straight line repair as this is becomes a possible hinge given enough force.(IMG:style_emoticons/default/beerchug.gif)

[URY914]

You need to mix a test batch. Forget about trying to measure.

Cut an old beer can in half, wash it out, pour 1/2" of resin in it and add 10 drops. Wait and see if t sets up.

Adjust the resin about or the hardener next time if needed.

Don't make this too hard.

I've been working on a revised air scoop for my car for the last several months. I've been making small batches about every night and weekends. After you've worked with it enough you get a feel for the ratio.

[Chris Pincetich]

Hey - my years of fixing surfboards can help a 914er (IMG:style_emoticons/default/beerchug.gif)

All of the above are great tips. Especially using an old beer can or metal throw-away container for a test batch. Use cardboard scraps as spreaders. Most resins do melt plastic.

Temperature is key to resin hardening time and even to the mix of catalyst/resin ratio. What works at 8am on a cold day will be way different than what works at 4pm on a hot day.

When I do fiberglass work I like to feel the "gel" form after 10-15 minutes. It will be unworkable after 20-25 minutes and fully cured the next day.

[bigkensteele]

I appreciate all the tips. I am going to try to pick this back up this weekend. I will update the thread with my progress.

[ruby914]

Sounds like you got a lot of good advice already.
Anything you can't peal off, cut off with a utility knife. You can try to clean off uncured resin with acetone. I wouldn't worry about whatever doesn't come off easy, It will cure over time.
Do try to get a smooth surface to lay your next batch on. you can use Bondo to fill holes. After the Bondo has gelled and before it gets too hard, you can trim and shave it with that utility knife. Or sand it after it gets hard.
I would think if you put drops of MEKP in your resin last time try a squirt next time.
Have fun.

[Eric_Shea]

How old was it Ken?

You need to have new resin and hardner.

I tried to use some old off the shelf stuff on an RV tank. Never hardened.

[bigkensteele]

How old was it Ken?

You need to have new resin and hardner.

I tried to use some old off the shelf stuff on an RV tank. Never hardened.

I have been in possession of the product for maybe 3 months. I can't speak to how long Napa may have had it on the shelf. I will look for a date code when I get home.

[Eric_Shea]

That's probably not it then.

[bigkensteele]

That's probably not it then.

I am pretty sure that it was user error. No date code one the resin can, so I poured some into a rag and huffed it. I then traded lead riffs on Voodoo Chile with Jimi Hendrix and a few minutes later had tea and hookers with Henry VIII, so the resin is probably still good.