Duramix Fiberglass Panel Adhesive--Any Good?

[Scott Marshall]

Has anyone used the Duramix brand panel adhesive? I was reading on their website that it can be used on Corvette panels. It comes in a two compartment cartridge you put in a what looks close to a caulk gun. I am considering using this method because of the ease of application. I am replacing my hood surround, front valance, and rear filler panels so I am trying to estimate the amount of adhesive I will need. I don't mind some excess but I don't want an extra gallon. Any rough estimate of how much I will need will be better than any guess I could come up with right now. Anyway, I was thinking of using either the Bondo, Evercoat, or Duramix brand adhesive. Any suggestions will be greatly appreciated.
Thanks

[Ed Jennings]

Re: Duramix Fiberglass Panel Adhesive--Any Good?

Haven't used it for that specific purpose, but we use it and other Duramix products routinely in my shop with good results. They make a wide range of products for fiberglass and urethane panel repair.

[Ed Jennings]

Re: Duramix Fiberglass Panel Adhesive--Any Good?

Haven't used it for that specific purpose, but we use it and other Duramix products routinely in my shop with good results. They make a wide range of products for fiberglass and urethane panel repair.

[Chuck S.]

Re: Duramix Fiberglass Panel Adhesive--Any Good?

Scott, check the website specs to see if the adhesive will work with SMC panels...I would expect most modern two-part adhesives in cartridges to work with either SMC or polyester resin panels. If your car had been later than a 72 (Read your profile; year is usually important), this would become a critical advantage. Polyester adhesives CAN NOT be used with SMC panels.

If your panels are polyester resin FRP, then the best adhesive for originality will be black tinted polyester adhesive available from The Corvette Image and other vendors. For a 72, reproduction panels will be polyester FRP. If you have somehow stumbled onto some GM service replacement panels, they may or may not be SMC. In that case, adhesive originality will not be an issue anyway if you use the SMC; most of the original 72 panels were FRP.

SMC will be a medium gray, possibly with black streaks or spots imbedded in the panel. Polyester FRP will be a dark charcoal or black color, and probably will have visible fiberglass strands embedded in the surface

[Chuck S.]

Re: Duramix Fiberglass Panel Adhesive--Any Good?

Scott, check the website specs to see if the adhesive will work with SMC panels...I would expect most modern two-part adhesives in cartridges to work with either SMC or polyester resin panels. If your car had been later than a 72 (Read your profile; year is usually important), this would become a critical advantage. Polyester adhesives CAN NOT be used with SMC panels.

If your panels are polyester resin FRP, then the best adhesive for originality will be black tinted polyester adhesive available from The Corvette Image and other vendors. For a 72, reproduction panels will be polyester FRP. If you have somehow stumbled onto some GM service replacement panels, they may or may not be SMC. In that case, adhesive originality will not be an issue anyway if you use the SMC; most of the original 72 panels were FRP.

SMC will be a medium gray, possibly with black streaks or spots imbedded in the panel. Polyester FRP will be a dark charcoal or black color, and probably will have visible fiberglass strands embedded in the surface

[Terry F.]

Re: Duramix Fiberglass Panel Adhesive--Any Good?

You need to find out if you have SMC or black fiber glass. I believe chuck said something about it. They stopped using the black fiberglass in around 1972 or so. Chuck talked about that.

I have used the duramix and I would not recomend it for black fiberglass application. It has a few problems related to its physical characteristics that I don't like. 1) It sets off too fast for doing large panels. With polyester panel adheisive, you can control the set off time by adding more or less hardener. 2) For me it tended to run out of vertical surfaces and made it very difficult to bridge gaps. If you replace enough panels you will realize that being able to fill large gaps is a must. Take apart a plastic car and you will find some huge gaps in some places. Watching the panel adheisive run out on the floor sucks and trying to spatula it back up in there is even worse. 3) After a couple of weeks, I thought that it dried too hard for my taste with regard to the application I was using it for (gluing a door skin on). It dried harder than the original stuff that had been there 35 years. 4) Probably good for small repairs, etc. but I don't like repairing any surfaces that will be painted with anything other than fiberglass. I say this because I don't know how it and the surrounding fiberglass will behave after heating up and cooling down through seasonal changes and just plain sitting in the sun. I prefer to used fiberglass resin with as little resin as possible and shrinking the repair with a heat lamp.

If I was going to bond fiberglass to metal, I would contact Lords Corporation. They make the products that are currently being used to glue figerglass to metal on much of the new corvette stuff that is being made in reproduction (that is, when I last looked into this sort of thing).

If I was going to bond SMC, I would contact Corvette Image and ask there recommendation. I would find something that closely approximated the original adheisive physical characteristics.

Good luck, Terry

[Terry F.]

Re: Duramix Fiberglass Panel Adhesive--Any Good?

You need to find out if you have SMC or black fiber glass. I believe chuck said something about it. They stopped using the black fiberglass in around 1972 or so. Chuck talked about that.

I have used the duramix and I would not recomend it for black fiberglass application. It has a few problems related to its physical characteristics that I don't like. 1) It sets off too fast for doing large panels. With polyester panel adheisive, you can control the set off time by adding more or less hardener. 2) For me it tended to run out of vertical surfaces and made it very difficult to bridge gaps. If you replace enough panels you will realize that being able to fill large gaps is a must. Take apart a plastic car and you will find some huge gaps in some places. Watching the panel adheisive run out on the floor sucks and trying to spatula it back up in there is even worse. 3) After a couple of weeks, I thought that it dried too hard for my taste with regard to the application I was using it for (gluing a door skin on). It dried harder than the original stuff that had been there 35 years. 4) Probably good for small repairs, etc. but I don't like repairing any surfaces that will be painted with anything other than fiberglass. I say this because I don't know how it and the surrounding fiberglass will behave after heating up and cooling down through seasonal changes and just plain sitting in the sun. I prefer to used fiberglass resin with as little resin as possible and shrinking the repair with a heat lamp.

If I was going to bond fiberglass to metal, I would contact Lords Corporation. They make the products that are currently being used to glue figerglass to metal on much of the new corvette stuff that is being made in reproduction (that is, when I last looked into this sort of thing).

If I was going to bond SMC, I would contact Corvette Image and ask there recommendation. I would find something that closely approximated the original adheisive physical characteristics.

Good luck, Terry

[Scott Marshall]

Re: Duramix Fiberglass Panel Adhesive--Any Good?

Now my question is a little more complicated. '72 Corvettes are fiberglass? or SCM? Not exactly sure what the difference is in the two, only that each one apparently needs its own adhesive. I plan to use the original existing bond strips for all the repairs. Can you bond an SMC panel where there was originally fiberglass. I suspect that some of my replacement panels may be either or. Is there an adhesive that does both types? I am not so concerned about the color originallity.
Thanks again,
Scott

[Scott Marshall]

Re: Duramix Fiberglass Panel Adhesive--Any Good?

Now my question is a little more complicated. '72 Corvettes are fiberglass? or SCM? Not exactly sure what the difference is in the two, only that each one apparently needs its own adhesive. I plan to use the original existing bond strips for all the repairs. Can you bond an SMC panel where there was originally fiberglass. I suspect that some of my replacement panels may be either or. Is there an adhesive that does both types? I am not so concerned about the color originallity.
Thanks again,
Scott

[Terry F.]

Re: Duramix Fiberglass Panel Adhesive--Any Good?

I am mainly familiar with black glass panels. You can buy reproduction black glass panels from Corvette Image out of Oregon. I believe they sell the original SMC stuff also. So...you can buy what belongs on your car.

Generally speaking I have never found an SMC panel adheisive that wouldn't bond both SMC and black fiberglass. I found it stated in the application summery that most suppliers provide. But, I have not found the same for those products that are specificly intended for black fiberglass. Those products only work for black fiberglass.

SMC....I believe it stands for Sheet Molded Composite. I believe it was an attempt to improve the paint surface of the former black fiberglass. SMC has a gelcoat for the outer layer. As you get deeper into the panel you find short choped strands of fiberglass and resin. I assume the resin to be polyester. If your car is SMC wipe off an area of the underside of your panels with some laqure thinner, they will be smooth, light gray, and show very little if any strands of fiber glass. If you see strands, they should be short and have a chopped appearance. That is the only way I can explain it. Anyone is welcome to correct me on this. It has been a while since I cut some SMC apart. I am only partially confident they used a gelcoat for the outer layer.

Black glass... Instead of a gelcoat, they sprayed a bunch of polyester resin in the mold first to form the outer layer (some people wrongly refer to this as a gelcoat). After that, they layed in long strands of fiberglass and polyester resin. If you sand a black glass car to much, you will break through that first layer of polyester resin that acts as a barrier and seals the strands in. But, even on original panels I have esentially seen where the fiberglass matting is at the surface of the panel.

Now, I have heard of continuous black fiberglass stranded and non-continuous black fiberglass panels. I am not sure if people were trying to distinguish between SMC or Black glass or what. I know that the original panels that I have been working with are black long continuous stranded. The repro people may have been doing something with non-continuous stranded black fiberglass for a while. It is like splitting hairs. I mention this stuff because I have heard about it in the past and I know people that split hairs over that sort of stuff.

I cut up part of a 72 vette and I seem to recall it had a black glass fire wall and SMC body panels. So...maybe they mixed and matched untill they ran out of one or the other.

Hope this helps, Terry

[Terry F.]

Re: Duramix Fiberglass Panel Adhesive--Any Good?

I am mainly familiar with black glass panels. You can buy reproduction black glass panels from Corvette Image out of Oregon. I believe they sell the original SMC stuff also. So...you can buy what belongs on your car.

Generally speaking I have never found an SMC panel adheisive that wouldn't bond both SMC and black fiberglass. I found it stated in the application summery that most suppliers provide. But, I have not found the same for those products that are specificly intended for black fiberglass. Those products only work for black fiberglass.

SMC....I believe it stands for Sheet Molded Composite. I believe it was an attempt to improve the paint surface of the former black fiberglass. SMC has a gelcoat for the outer layer. As you get deeper into the panel you find short choped strands of fiberglass and resin. I assume the resin to be polyester. If your car is SMC wipe off an area of the underside of your panels with some laqure thinner, they will be smooth, light gray, and show very little if any strands of fiber glass. If you see strands, they should be short and have a chopped appearance. That is the only way I can explain it. Anyone is welcome to correct me on this. It has been a while since I cut some SMC apart. I am only partially confident they used a gelcoat for the outer layer.

Black glass... Instead of a gelcoat, they sprayed a bunch of polyester resin in the mold first to form the outer layer (some people wrongly refer to this as a gelcoat). After that, they layed in long strands of fiberglass and polyester resin. If you sand a black glass car to much, you will break through that first layer of polyester resin that acts as a barrier and seals the strands in. But, even on original panels I have esentially seen where the fiberglass matting is at the surface of the panel.

Now, I have heard of continuous black fiberglass stranded and non-continuous black fiberglass panels. I am not sure if people were trying to distinguish between SMC or Black glass or what. I know that the original panels that I have been working with are black long continuous stranded. The repro people may have been doing something with non-continuous stranded black fiberglass for a while. It is like splitting hairs. I mention this stuff because I have heard about it in the past and I know people that split hairs over that sort of stuff.

I cut up part of a 72 vette and I seem to recall it had a black glass fire wall and SMC body panels. So...maybe they mixed and matched untill they ran out of one or the other.

Hope this helps, Terry

[Wayne W.]

Re: Duramix Fiberglass Panel Adhesive--Any Good?

Corvette panels were molded polyester fiberglass until 1969 when a new material, Genite, made by General Tire and Rubber Co. was introduced. The first Corvette panel made from this new material was door panels on later 69`s. The Genite panel had a better surface and was easy to prep for paint. Other Genite panels were added to the line until 1971 when SMC was introduced. The first SMC panel used was on 1971 rear fenders. Again new panels were added until 1974 when the changeover was complete and all panels at least exterior ones were SMC. Yes the factory used a mixture for several years. As for bonding, any agent that will bond SMC will bond the others. They are epoxy based materials. But some epoxy materials are not very good on the surface for surface filling and finishing so keep that in mind when asking your supplier for the correct material.

[Wayne W.]

Re: Duramix Fiberglass Panel Adhesive--Any Good?

Corvette panels were molded polyester fiberglass until 1969 when a new material, Genite, made by General Tire and Rubber Co. was introduced. The first Corvette panel made from this new material was door panels on later 69`s. The Genite panel had a better surface and was easy to prep for paint. Other Genite panels were added to the line until 1971 when SMC was introduced. The first SMC panel used was on 1971 rear fenders. Again new panels were added until 1974 when the changeover was complete and all panels at least exterior ones were SMC. Yes the factory used a mixture for several years. As for bonding, any agent that will bond SMC will bond the others. They are epoxy based materials. But some epoxy materials are not very good on the surface for surface filling and finishing so keep that in mind when asking your supplier for the correct material.

[Terry F.]

See Wayne's post. *NM* *NM*

[Terry F.]

See Wayne's post. *NM* *NM*