Fiberglass repair?

[Tom L.]

I have the evaporator housing out of the car and there's a little damage to it, I guess from an engine removal. The patch on the outside is about 10" in diameter, and crudely done, but the hole is a little less than the size of a quarter. Any ideas how to make a repair that will look more "press molded" like and retain a similar color to the area's surrounding it?? Thanks!!!

[Graeme B.]

Re: Fiberglass repair?

Hi Lynn,
You could put some tape over the hole and fibreglass it from the inside.You can put colouring into the resin to darken it.
Or you can do a little mold over the area of the hole in bodyfiller and smooth off the lump left by the hole .Then place the temporary mold back in position and glass into that. Clear as mud? Good luck, Graeme.

[Russ S.]

Re: Fiberglass repair?

The correct way to do it is to contour the hole out from the front side, put tape on the back side, and then with a slight amount of black dye in the resin, glass the front side with resin and mat. Cure it, sand it, and then remove the tape from the back side and do the same on the back side as you did on the front.

[Graeme B.]

Re: Fiberglass repair?

Or ,as Russ said, you can do it the "correct way".

[Tom L.]

Re: Fiberglass repair?

Having never worked with fiberglass I'm new at this. What type of resin and matt, and where can I buy these materials. Also, when sanding what grit sand paper to use that will not scuff the surface around it to make the repair look obvious? What type of dye? Finally, how much working time is there and how much time to cure before sanding? Thanks for the help!!

[Larry M.]

Re: Fiberglass repair?

Having never worked with fiberglass I'm new at this. What type of resin and matt, and where can I buy these materials. Also, when sanding what grit sand paper to use that will not scuff the surface around it to make the repair look obvious? What type of dye? Finally, how much working time is there and how much time to cure before sanding? Thanks for the help!!

Lynn:

Give Scott Sinclair a call. He posts on this board and advertises in the Driveline regarding tire tub repairs. He did my 1967 tire tub. repair. I think he also does other small jobs. Excellent work and easy to drop off and pick up the parts at various shows and events.

Scott knows how to do these repairs and has the resins and color agents, etc. etc.

Larry

[Russ S.]

Re: Fiberglass repair?

Having never worked with fiberglass I'm new at this. What type of resin and matt, and where can I buy these materials. Also, when sanding what grit sand paper to use that will not scuff the surface around it to make the repair look obvious? What type of dye? Finally, how much working time is there and how much time to cure before sanding? Thanks for the help!!

Lynn, You can usually get the supplies at a auto parts store except probably not the dye. Resin should be a polyester based. Don't use the cloth fiberglass but instead use the matted glass. I typically use 80 grit paper to sand. If you are concerned with scratching the surrounding area start out with 80 grit and when you get close to the finished surface go with a finer grit-probably about 120. Working time will vary greatly with the amount of hardener you use. Typically I use 10-13 drops in apprx. an ounce-1-1/2 ounce of resin and it gives me about eight minutes working time. Use a 3/4-1 inch wide paint brush to apply the resin.

[Alan S.]

Re: Fiberglass repair?

Hi Lynn,
I had a couple of small fiberglass repairs to do and used lamp black to tint the resin.
I did some resin tests first, (4-5), to get it dark enough to match the repair area.
It's not too bad a job!
Regards,
Alan

[Michael M.]

Re: Fiberglass repair?

Lynn, if you get the correct tints ( black and maybe some white ) for fiberglass resin you only need very little to change the color of the resin. Do some test mixtures until you get the desired color before using the hardner.

[Tom L.]

Re: Fiberglass repair?

Thanks for the replies. What are you using as tints? Did some "googling" and found that Bondo brand fiberglass repair materials seem to be redily availible. Are these reasoable to use? As always, thanks for the replies, been a great help!

[Loren L.]

Re: Fiberglass repair?

I would Second Larry's suggestion - Scott's been there before and knows the how & Why.
Regards,
LL

Lynn:

Give Scott Sinclair a call. He posts on this board and advertises in the Driveline regarding tire tub repairs. He did my 1967 tire tub. repair. I think he also does other small jobs. Excellent work and easy to drop off and pick up the parts at various shows and events.

Scott knows how to do these repairs and has the resins and color agents, etc. etc.

Larry

[Donald H.]

Re: Fiberglass repair?

I'm no expert, but I did a lot of patching on my 60. I used products from Fibre Glast (you can Google the name). Their products were recommended by a Vette body man/painter of 35 years. He recommended their Isophthalic Polyester resin. They sell in as small as 1 quart. They also sell tinting agent in many colors. I used this to match the underside of my 60. The key is you will use very little of the tinting. I used a wooden tooth pick to put a dab of tint in one ounce of resin then added the hardener and mixed. The resin should be sort of translucent when tinted and not a solid color. You will end up using much less of tint than you will originally think once you experiment with it some.

Once I did the patch and sanded with 80 grit I used another mix of resin to rub over the patch and let it sit for just a couple of minutes, then I wiped it off with a rag with some acetone on the rag. I got a surface that looked pretty much like the factory finish.

If you only have a small area to do you can pick up fiberglass mat at a lot of Auto supply stores. Fibre Glast only sells in larger quantities.

[Bill H.]

Re: Fiberglass repair?

I have the evaporator housing out of the car and there's a little damage to it, I guess from an engine removal. The patch on the outside is about 10" in diameter, and crudely done, but the hole is a little less than the size of a quarter. Any ideas how to make a repair that will look more "press molded" like and retain a similar color to the area's surrounding it?? Thanks!!!

A pic would help, curious about the 10" repair, how do you plan to remove that ?
It's good that the housing is off the car and you can get to the back side. After you remove the "crude repair", the edges of the hole need to be tapered, this gives you more surface area and clean glass for the new glass to bond to. You can taper the edges with a Dremel, sandpaper or a round file
Since it's a small hole, I'd try to glass both sides at the same time. Clean the back side of the hole to remove any dirt/oils. Sand the area with 80 to give the new glass a good surface. Cut a patch from the mat that's at least 1/2 inch bigger than the hole (for the back side).

When you get the old patch removed and the outside of the case the way you want it to look, cut 2 round pieces of mat that fit the quarter sized hole, cut another round piece of mat that fits the diameter of the tapered edge of that hole.
On the outside of the case, put masking tape around the hole very close to the repair area, this will keep the resin off the good glass. It also goves you an indicator where to stop sanding with the course sandpaper, when hit the masking tape while sanding, switch to a finer grade of sandpaper.

Mix the resin exactly as the instructions show, don't go overboard with the hardner.
Lay the patch on the back side making sure the air bubbles are pushed out with your brush. Cover the entire patch and 1-2 inches beyond it with 2 inch masking tape, yes over the wet glass.

Put the 3 pieces of round mat into the hole on the outside again working any bubbles out to the edges.

This way the new glass bonds together on both the front and back and makes a very strong repair.

The prducts from Fiber Glast are very good but for this repair, I'd get the stuff locally.

I like the 3M resin a bit better than Bondo.

The local Home Depots here carry the 3M resin in the paint dept.

[Tom L.]

Re: Fiberglass repair?

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Thanks, I did get the 3M resin at the depot today, along with the mat. After a bunch of research I have a plan simiar to yours. Thanks for the detail, all information helps. I've attached a pics of the hole.

The "patch" was easily removed. The last owner went crazy with black spray paint. While removing it with "Zip-Strip" I noticed that the edges loosened. I soaked the patch and it peeled off easily.

[Bill H.]

Re: Fiberglass repair?

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Thanks, I did get the 3M resin at the depot today, along with the mat. After a bunch of research I have a plan simiar to yours. Thanks for the detail, all information helps. I've attached a pics of the hole.

The "patch" was easily removed. The last owner went crazy with black spray paint. While removing it with "Zip-Strip" I noticed that the edges loosened. I soaked the patch and it peeled off easily.

Yep, the old patch came loose becaues of improper prep.

This isn't a real hard repair.

Make sure the inside patch area is spotlessly cleaned and scuffed, the outside edges of the hole tapered and scuffed.

I'd follow the other guy's suggestions on tinting the resin.