Epoxy/fiberglass kicked my butt

Thomas,Take it from a guy who works with fiberglass everyday. It is a work of art just like any other "craft" don't expect professional results the first time you use it. Just like woddworking it takes time, patience and experience to master it.

The key to doing corners is to cut your glass in circles making them a little larger each time. Place the center of your circle on the corner and form around it. Once you get the thickness you need I'd suggest taping the corners with a heavy duty PLASTIC tape. WE use a special made tape for fiberglass at DAL but I think that a heavy duty packing tape might work. Just make sure that the strips of tape are narrow so that they can form around the corner well. Make sure they are long enough to secure your repair and then some. I don't know if the tape will withstand the heat from the resin curing but hey, its worth a try. Could even try saran wrap but not sure it that would work either. It might stick to your repair but then again???? The KEY to this is COMPRESSION!!!! the more compressed your layers of glass are, the stronger the repair will be.

   As far as your resin goes....That is the nature of the beast. A larger mass will cure faster than a small thinned out portion because the heatgenerated by the curing process. It does start a chemical chain reaction.
More volume of resin = more heat = quicker set up time.
The way do slow the beast is to mix smaller amounts of resin OR use a drop or two LESS of catalyst. {If it calls for 10 drops on a 80'F day then use 7 or 8.} It will buy you a little time. Acetone will thin the resin so that the cloth will soak up the resin a little better. It may buy you some time but not real sure on that one. I work with non-epoxy based resins so don't know for sure.

Another key to epoxy resin repair is to have all your layers of glass PRE-CUT!!! Have the ENTIRE repair in front of you in the order in which they go so that the next layer of glass is already precut to fit. You don't want to play " Cut as you go". This will buy you all kinds of time. I'd rather the resin wait on me then vice versa cause the resin will win eventually.

One final tip is that you can make sure of complete glass penetration is to heat up the repair with a hair dryer or heat gun if you have one. This will cause the resin to become less viscous and "flow" into the cloth. This is where compression fits in. You want to ELIMINATE the possibility of air pockets. These will weaken your repair. The draw back to this of course is heat and heat is....

Hope this helps. Let me know if you need anymore help be glad too. This goes for anyone else too...

Morfoot

" If it doesn't fit, then get a bigger hammer!!!"

tleed,

I'm no expert but here are a couple of tips that might help:

1. For inside corners, make sure you "fillet" them. That means, you apply thickened resin (structural filler) into the corner to make it smooth and rounded. You'll never get the cloth to lay in a sharp 90-degree bend. Even if you did, it would not be strong.

2. I always spread resin with a spreader, i.e. a flat plastic spatula-looking thing. It's easy to squeeze the resin into the cloth this way.

3. Circles are better than squares for corners because the corners of the squares would be harder to lay down. (haha)

4. The West System stuff that I've used has several different types of hardeners for different cure rates. Use the slowest one if you are running out of time. Chilling the materials beforehand will also slow the cure. I wouldn't mess with resin/hardener ratios if I were you.

5. I happen to know that Saran Wrap (well...the local generic brand) does NOT stick to cured resin (you should test your own). So, I can imagine several ways to apply pressure to your repairs: For inside corners, you might try a bag of sand. For outside edges, how about compressing a big block of foam (covered with saran wrap) over the corner with tape; or maybe sand would work for this as well?

6. I noticed you said, "mat." For edges and corners, the cloth is much more flexible and "moldable" than mat.

7. West System has a lot of good info on their website and in their inexpensive publications:
http://www.westsystem.com/webpages/userinfo/manual/index.htm

David, I have no idea what "axial roving" and "fillet" mean. My fiberglass repair materials say "mat" and "cloth" on them.

Does axial roving=cloth and fillet=mat?

Thomas

I have found that dipping your gloves and roller in acetone while working will help keep the fiberglass from sticking to you.

Here are some terms I use:

woven roving = the cloth you see everywhere.

mat = random fibers held together in a mat with a binder. Epoxy resins do not disolve the binder (only polyester).

epoxy mat = same as above, but fibers are held in place with stitching, not a binder.

axial roving = all fibers run in one direction and are held together with stitching.

There are many others...check out www.uscompsites.com for all the different types of mat and roving. There are also many different weights of each.

In the heat of the summer and being a beginner, you are best served by purchasing a slow cure or long pot life epoxy. No that we are having 100 degree days here in Austin, even the medium pot life epoxy gives me trouble. I generally only mix batches of 4 oz. at a time to avoid wasting epoxy due to gelling in the cup. Buy 9 oz. waxed paper cups and use popcicle sticks for mixing.

AH HA!!!! See I told you, Experience and wisdom goes a long way. Its not as hard as it seems with practice you too will learn the ways of fiberglass repair my young Padawan!!

Sure:

Pre-wet the pieces of cloth/mat before slapping them into place, makes the in-place wetout, much esier. I pre-wet on waxed paper.

A utility knife works great to trim excess, if you do it in the curing stage before the composite fully hardens.

Cloth and mat should be used for best ultimate strength.

Cheap/disposible paint brushes work best for applying resin in most situations (other than large flat horizontal areas).