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General Tech Bondo

DavidApp

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Hello All

A Bondo question.

Will working bondo too long tend to make it not setup properly?

The same batch of bondo seemed to set up hard in one area and is still rubbery in another area. I am sure I got it mixed up properly with no streaking in the mix. The first area I did set up hard but the last area did not.

David
 

TomMull

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Lots of reasons for polyester not curing or curing slowly. Working it too long will accelerate the cure, not inhibit it. Is the Bondo or hardener old? If so get a new batch. Did you use enough catalyst? I always buy a separate tube since I find that if I still have catalyst left at the end of the can, I haven't used enough. I think you can rule out cold temperature this time of year in Macon, but the stuff is very temperature sensitive. It is at least warm to the touch when curing (exothermic) and ambient heat will accelerate the curing, so you might try a heat lamp on the patch or if possible ut the project in the sun.
Try a test batch, catalyze and mix it for one minute and then leave some in a glob and spread some thin on a piece of cardboard. The glob should heat up and solidify in 10 minutes or less, the thin stuff should take twice as long or so. Careful though, a grossly over catalyzed batch can heat to the point of combustion.
Tom
 

dklawson

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I have never seen Bondo develop different textures based on how long it was worked, only how much hardener was added and how well it was mixed. I suppose if the Bondo was really old and had started to dry up and/or separate in the can you could have curing problems. New Bondo will have a very smooth texture throughout while older stuff will be grainy.
 

CJD

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+1 to the old can.

Your case sounds like it was not mixed thoroughly. If you are certain that it was, then you have an old can (or bad tube of methyl ethyl ketone hardener). Just because it was bought new yesterday does not necessarily mean it is not old. Many stores don't move it fast, so you can get a can that has sat on the shelf for years. If you bought it recently they will likely even take it back.

But worse...if it does not cure overnight you will have to grind that junk off and start over.

Note: Just thinking...the original bondo was, well, the original...but it is no longer the best. If you have to buy more, go to a real automotive paint shop and buy Evercoat Rage. It applies smoother and sands a million times easier than Bondo.
 
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DavidApp

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Hello Tom, Doug and John

I am using Evercoat bought at a automotive paint store on the assumption they would move more stock than a car parts store.

Just peeled it off the panel and cleaned up all vestiges of it. Still pliable but the other area set up normally. Going to put it down to operator error.

Mixed up a small batch about 30 minutes ago and it set OK.

Thank you.

David
 

CJD

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Then you should be good. Glad to hear you're into the final stage before painting! Be sure to post a pic now and then...I'm pretty board without a project. I have to live vicariously through you guys now.
 

M_Pied_Lourd

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Cmon up here John...ill put you to work :wink-new:

Cheers
Tush
 
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DavidApp

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I have a long way to go. In Georgia this time of year it is so humid that if you sand blast something you have to cover it as soon as possible. I understand bondo should go on before primer. I may be going a bit backwards in my work flow but I am also working on my skill set.
Trying to get everything on the tub to fit so I can align and weld the outer sill on the drivers side. Then I need to get the tub off the frame to get to the floor pan to tunnel seam the PO made a botched up job of it. I could not get to it with it on the frame so I decided to do that last before blasting and painting the tub. May be cooler and dryer by then.

This is his work.
Under side of floor to tunnel.jpg

David
 
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DavidApp

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That is the good area of the seam!!

If I knew then what I knew now I may well have cut the floors out and started over . May have saved me some time and trouble.

David
 

CJD

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aahh. What would we have to do if it wasn't for DPO's? Thanks for the fix! And Tush, you know I'd be over every day if you lived a couple thousand miles closer!
 

dklawson

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Keep at it. You'll get it where you are happy.

Humidity is also a year round problem here. If it is not too late, consider buying an epoxy primer that is compatible with your topcoat system. The epoxy will seal the surface against moisture better than "regular" primer. That will give you more time to prep the car. You need only roughen the epoxy primer a bit to apply filler on top of it.
 

CJD

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Doug is right...my supplier is always telling me to epoxy prime under the filler. I still don't do it that way...but it is the preferred way of doing it. That will solve your flash rust problem too.
 

M_Pied_Lourd

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:cool: funny, were are all a little bit old school...I like to do my filler work directly on bare metal even though I know I can do epoxy primer and do my filler work over the top of that with proper prep...
Maybe on my 250 I'll try and break out of my shell and go outside of my comfort zone!

Cheers
Tush
 

kstanley44

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Not ready for the tub yet, but when picking up epoxy primer for my chassis my supplier also said epoxy prime first, then filler and then epoxy prime. Sort of a sandwich approach. Make sense? Chassis looks nice in PPG epoxy primer.
IMG_2690.jpg
 

CJD

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Nice chassis! I am sure the idea is that filler is actually very porous, so if the finish is chipped down to the filler it could wick water in to the steel, causing rust. Again, I know the correct way, but just haven't brought myshelf to try it.
 
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DavidApp

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Any idea what the small straight clip is for? It goes vertically on both sides just in front of the throttle shaft.

David
Inside tub.jpg
 

CJD

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The steering column seal folds over the corner and tucks into that tab. I'll see if I have a decent pic...

Nope, it's kinda hidden once everything is together. This pic should give you the idea:

ee8RNdv.jpg


I have not tucked the seal in in this pic, but it shows how the column seal is large enough to wrap around the corner of the firewall and then tuck into the slot.
 
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DavidApp

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Hello John

Thank you.
Knew it had to be for something. Set up for RH or LH drive.

Got a coat of epoxy primer on the front Apron, drivers wing and door.Going out of town again for 2 weeks and knew it would be red rust if I left it.

David
 

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