Fiberglass panel bonding
12-11-2006, 12:45 AM
#1
Safety Car
Thread Starter
Fiberglass panel bonding
I've been going through a few 'how to' books to bone up on doing some panel replacements on my '64. Looking to replace the left front top fender, parking panel, and upper and lower nose panels.
The how-to books describe several different methods of finishing off the joint between panels that have a bonding strip backing. The glas-ra book says to scrape away the excess adhesive that oozes out between the joint once the replacement panel is set in place. This would seem to mimic the factory method of doing it.
The Eckler's book shows the joint (after the bonding adhesive cooks off) being grinded down so that mat and resin can be applied in the void of the ground down joint. Once cured the joint is finish sanded to contour.
Using Eckler's method would seem to offer the strongest joint repair. The glas-ra way of doing the repair would seem adaquate, also. What is the most common method used? ..
The glas-ra book mentions using 'bond spacers' between the panels being bonded. These spacers appear to be some kind of soft material that will allow the gap between the bonding strip and panel adhesive to not be too thin when the panels are squeezed against the bonding strip upon installation. Are these really needed? .. Is there some other material that can be used? .. How thick should the bonding adhesive between the bonding strip and panels be? ..
Bonding adhesive: In looking through the archives I found 3M, Fusor, and Norton being mentioned as bonding adhesives. I'm hoping to use a product that has a long setup time - say, something on the order of an hour? .. Which bonding adhesive have you guys used that has a long working time? ..
This will be my first time doing panel repairs. I'm not exactly sure what to expect so something that lights off in 5-15 minutes might be cutting it close! ..
The how-to books describe several different methods of finishing off the joint between panels that have a bonding strip backing. The glas-ra book says to scrape away the excess adhesive that oozes out between the joint once the replacement panel is set in place. This would seem to mimic the factory method of doing it.
The Eckler's book shows the joint (after the bonding adhesive cooks off) being grinded down so that mat and resin can be applied in the void of the ground down joint. Once cured the joint is finish sanded to contour.
Using Eckler's method would seem to offer the strongest joint repair. The glas-ra way of doing the repair would seem adaquate, also. What is the most common method used? ..
The glas-ra book mentions using 'bond spacers' between the panels being bonded. These spacers appear to be some kind of soft material that will allow the gap between the bonding strip and panel adhesive to not be too thin when the panels are squeezed against the bonding strip upon installation. Are these really needed? .. Is there some other material that can be used? .. How thick should the bonding adhesive between the bonding strip and panels be? ..
Bonding adhesive: In looking through the archives I found 3M, Fusor, and Norton being mentioned as bonding adhesives. I'm hoping to use a product that has a long setup time - say, something on the order of an hour? .. Which bonding adhesive have you guys used that has a long working time? ..
This will be my first time doing panel repairs. I'm not exactly sure what to expect so something that lights off in 5-15 minutes might be cutting it close! ..
12-11-2006, 05:26 AM
#2
Racer
You first need to clean the epoxy, within limits, off of the old joint to insure a smooth junction. I never found a need for "spacers" as the union is not that thick. I did predrill a few holes for hardware, for holding the part in place, being sure not to tighten down too much. I left the "excess" in place for a couple of weeks, to allow the bonding material to settle, then I sanded it smooth. It does set quickly so have everything set to go ahead of time.
12-11-2006, 08:22 AM
#3
I've used bonding adhesive from corvette Central and Ecklers. Your time frame will all depend on how much hardener you add to the mix. Too much and it will cure in 5 minutes, too little and it will never cure fully. Since it is winter you will have more working time. That stuff sets up really quick when it is 75+ outside. Overall both products worked well and i think you can buy both products in the original color. You will want to spend the extra money on the correct color, otherwise you will end up with a color that looks like pink bondo.
12-11-2006, 08:37 AM
#4
Panel Bonding
Starting at the beginning, Grind off all the old adhesive down to the bonding strip. Depth of the grind will be determined alot by the difference in colors of the old panel adhesive & the bonding strip itself.
As far as using/not using "spacers" will be determined by how even/uneven the new panel sits with relation to the panels around it. On a recent top surround job, in some areas "spacers" were required/others not. BTW, I don't believe the spacers are "soft", I think they are made from scraps of the damaged panels (rigid). At least that's what I used. I ground some thick, others thinner.
Trial fitting is very important, measure, fit, measure, fit, etc.
On the top surround I used 3M 8515 adhesive, It has a working window of 60-90 minutes & I found that factor alone took out ALOT of the stress & improved the quality of the finished job tremendously.
The 3M adhesive is a little pricey, in my opinion, about 30-35 for a two tube container & the kicker is that it can only be used with 3M's gun. The gun lists for 325.(I was lucky enough to borrow one). Norton also has a very similar product (have not used it) that sells for 20. & I understand that it can be used in almost any cartridge gun. It also has a 60-90 window. Can't comment on Fusor products But I've read a number of good reports re it.
Whether to scrape/leave the excess adhesive I think depends on what final results you're after. If you want "factory" look, scrape it off even with the top of the panels & if you're going to put 'glas & resin in/on the gap (which I did), then you would probably want to remove most of the exposed adhesive.
HTH, Bob L.
As far as using/not using "spacers" will be determined by how even/uneven the new panel sits with relation to the panels around it. On a recent top surround job, in some areas "spacers" were required/others not. BTW, I don't believe the spacers are "soft", I think they are made from scraps of the damaged panels (rigid). At least that's what I used. I ground some thick, others thinner.
Trial fitting is very important, measure, fit, measure, fit, etc.
On the top surround I used 3M 8515 adhesive, It has a working window of 60-90 minutes & I found that factor alone took out ALOT of the stress & improved the quality of the finished job tremendously.
The 3M adhesive is a little pricey, in my opinion, about 30-35 for a two tube container & the kicker is that it can only be used with 3M's gun. The gun lists for 325.(I was lucky enough to borrow one). Norton also has a very similar product (have not used it) that sells for 20. & I understand that it can be used in almost any cartridge gun. It also has a 60-90 window. Can't comment on Fusor products But I've read a number of good reports re it.
Whether to scrape/leave the excess adhesive I think depends on what final results you're after. If you want "factory" look, scrape it off even with the top of the panels & if you're going to put 'glas & resin in/on the gap (which I did), then you would probably want to remove most of the exposed adhesive.
HTH, Bob L.
12-11-2006, 10:25 AM
#5
Melting Slicks
Midyearnut is on the money with his opinions. I would just add, be extremely patient with your preperations. You can't shine #%*$! A good start results in a good finish. Trial fit is very important and is representative of how the panels will look upon completion. And, YES, do remove excess squeezed out bonding agent. A novice will most often distort a panel with a grinder or overly aggressive sanding. Al W.
12-11-2006, 11:20 AM
#6
Not sure if these will help, but hopefully they will.
After you break the panel that you want to replace away from the bonding strip you will most likely end up with something that looks like these pictures. Lots of old bonding adhesive with strands of glass from the old panel as well.
I used a DA sander with 80-100 grit to remove the majority of the adhesive and then when i was close to the glass i switched to around 150-200 grit on the da and carefully took it down the rest of the way until i had a clean, but still somewhat rough surface. The bonding adhesive will stick better to a rough surface.
Pics after sanding-not a very good one-sorry
In most of the quarter panel areas i just let the adhesive drip, but on panels that are seen i smoothed out the adhesive with plastic disposable sheetrock paddles and my gloved fingers. I found plastic paint tray liners to be perfect for mixing the adhesive in and then i just used those little disposable paddles to apply the adhesive. I used a ton of c-clamps to hold my panels in place. I only used spacers on the rear quarters and honestly, they just ended up making the panel more difficult to work with. You can make your own spacers, if you really need them, out of cut up wooden paint paddles.
Here is a pic of an area that i smoothed with my gloved finger.
After you break the panel that you want to replace away from the bonding strip you will most likely end up with something that looks like these pictures. Lots of old bonding adhesive with strands of glass from the old panel as well.
I used a DA sander with 80-100 grit to remove the majority of the adhesive and then when i was close to the glass i switched to around 150-200 grit on the da and carefully took it down the rest of the way until i had a clean, but still somewhat rough surface. The bonding adhesive will stick better to a rough surface.
Pics after sanding-not a very good one-sorry
In most of the quarter panel areas i just let the adhesive drip, but on panels that are seen i smoothed out the adhesive with plastic disposable sheetrock paddles and my gloved fingers. I found plastic paint tray liners to be perfect for mixing the adhesive in and then i just used those little disposable paddles to apply the adhesive. I used a ton of c-clamps to hold my panels in place. I only used spacers on the rear quarters and honestly, they just ended up making the panel more difficult to work with. You can make your own spacers, if you really need them, out of cut up wooden paint paddles.
Here is a pic of an area that i smoothed with my gloved finger.
Last edited by Corbrastang; 12-11-2006 at 11:26 AM.
12-11-2006, 11:17 PM
#7
Safety Car
Thread Starter
Thanks, guys, for posting the great info and sharing your experience. Thanks too for providing the pics, Corbrastang. Those are a big help compared to the crummy B/W pics in the books! . .
That's interesting that the 3M product can only be applied with 3M's special gun. My thought was to use a regular caulking gun and blank cartridge tube that can be filled with bonding adhesive for use as an application tool.
That's interesting that the 3M product can only be applied with 3M's special gun. My thought was to use a regular caulking gun and blank cartridge tube that can be filled with bonding adhesive for use as an application tool.
