Epoxy over urethane

[79TransAm]

Sorry for my laziness for not searching for the answer.
Here is the situation. I'm restoring a 79 Trans Am. Bumpers are in great condition, just faded and rough.
My plan is either A- sand with 120 and finish with 180 DA. Shoot a coat of adhesion promoter then 3 coats of medium Epoxy. Then 2 coats of urethane 2k regular build primer. Block to 400, sealer bc cc. IS that right?

OR

can I skip the 2k, then put 2 more coats of epoxy and block to 400. When ready for paint, sealer. Will this crack? Seems to be a chip resistant attack. ANY thoughts based on experience? Not too worried about flex agents unless needed for epoxy. If it gets hit, will need to be done anyway. Thanks

 

[flynams]

Sorry for my laziness for not searching for the answer.
Here is the situation. I'm restoring a 79 Trans Am. Bumpers are in great condition, just faded and rough.
My plan is either A- sand with 120 and finish with 180 DA. Shoot a coat of adhesion promoter then 3 coats of medium Epoxy. Then 2 coats of urethane 2k regular build primer. Block to 400, sealer bc cc. IS that right?

OR

can I skip the 2k, then put 2 more coats of epoxy and block to 400. When ready for paint, sealer. Will this crack? Seems to be a chip resistant attack. ANY thoughts based on experience? Not too worried about flex agents unless needed for epoxy. If it gets hit, will need to be done anyway. Thanks

If it works, all epoxy is better

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Sorry for my laziness for not searching for the answer.
Here is the situation. I'm restoring a 79 Trans Am. Bumpers are in great condition, just faded and rough.
My plan is either A- sand with 120 and finish with 180 DA. Shoot a coat of adhesion promoter then 3 coats of medium Epoxy. Then 2 coats of urethane 2k regular build primer. Block to 400, sealer bc cc. IS that right?

OR

can I skip the 2k, then put 2 more coats of epoxy and block to 400. When ready for paint, sealer. Will this crack? Seems to be a chip resistant attack. ANY thoughts based on experience? Not too worried about flex agents unless needed for epoxy. If it gets hit, will need to be done anyway. Thanks

If it works, all epoxy is better

 

[Mike.]

I Agree on ad pro and epoxy only on bumpers from exp. Just a word of caution tho, have you ever used a DA on plastic before? If not be careful and be gentle with the sander.

 

[Bob Hollinshead]

no need for adpro on urethane covers, just make sure they are sanded and very very clean. All epoxy is definitely best!

 

[79TransAm]

Glad to hear all epoxy will work great. Just to be safe, I will go with ad pro on the top part as the top of the bumper is a bit more flimsy and smooth and I won't take all of that paint off. The face is more solid and since it is already rough, it will have a good mechanical adhesion when cleaned. I guess the need for it is optional, but not for plastic. Should be ok...works for me...and yes easy on the DA, I will just hand block to be safe.
Chip resistant all epoxy, here I come.
Thanks guys.

 

[RodMan]

If using adpro mixing it with primer activator will give even better adhesion. I believe mix ratio is 5 parts adpro to one part primer activator (any one of spi 2k activators will work)

 

[Revolver]

When I do rubber bumpers on older cars (2nd gen T/A's and 80's Cutlass's) I try to use light coats of primer, or not as many all at once. Never used adpro's or flex. No problems. My thinking is to keep the mills down on anything that isn't steel or fiberglass.

 

[79TransAm]

When I do rubber bumpers on older cars (2nd gen T/A's and 80's Cutlass's) I try to use light coats of primer, or not as many all at once. Never used adpro's or flex. No problems. My thinking is to keep the mills down on anything that isn't steel or fiberglass.

The vote is in. No flex, no adpro and light coats......works for me. Thanks guys.

 

[Revolver]

Currently doing front/rear bumpers for a 87 Cutlass. Da sanded with 80 grit, plus a lot of hand sanding in the nooks and crannies. Sprayed 2 coats of epoxy. Gotta sand some spots and go from there.