Bumper repair

[SMOKDU]

My bumper over the years has had some flames and paint damage. Can I bead blast the paint off ? My body guy wants me to do this so the paint sticks better. What is the bumpers shell made of anyway and is it safe to do this?

 

[roketman]

Time for a GTG Bumper delete !

 

[Sinovac]

The bumper cover is plastic, like the rockers and nose. Sand it and prep it properly for paint, and there will be no problem with paint adhesion. I would not bead blast any plastic panels.

 

[Cobrar]

The bumper cover is plastic, like the rockers and nose. Sand it and prep it properly for paint, and there will be no problem with paint adhesion. I would not bead blast any plastic panels.

This, from an attorney??!!?? Pretty darn close, though. :biggrin:thumbsup

Ford GT front and rear fascias, as well as the rockers are made from a thermoset material and process referred to as RIM (contrasted with 'plastic' generic which is thermoplastic). This link is not from the original GT supplier, but if you wish, you can read more here: http://en.wikipedia.org/wiki/Reaction_injection_molding

To answer your question, surface prep for painting is exactly as Paul described it. I would also add that if the topic comes up, do NOT heat the parts either. It will distort them permanently.

 

[SMOKDU]

This, from an attorney??!!?? Pretty darn close, though. :biggrin:thumbsup

To answer your question, surface prep for painting is exactly as Paul described it. I would also add that if the topic comes up, do NOT heat the parts either. It will distort them permanently.

Heat? it saw flames lol... My painter wants to strip it and then bake it in the booth. is that a bad idea ?

 

[Cobrar]

The 'heat' from the exhaust flame (unburnt fuel on decel?) is likely just oxidation of the adjacent painted surface and would NOT be comparable to a bake oven where the part is subjected to a continuous level of high heat over time. 1st step is to ensure that physical part damage has not occurred to your rear fasica. You can tell if there is physical damage - e.g. part has distorted/warped or the surface has very small bubbles in the part surface (degassed).

The original front and rear GT fascias were molded, then shipped to an intermediate supplier who painted them with a red spot primer and then hand sanded. Fascias were then painted along with the car to gain color match, but were placed on separate racks, so that the fascias could be fully supported. If the fascias were not fully supported in the bake process, the high temp environment (+275F) may cause the parts to incur deflection/distortion.

As to painting, or OE repair, one of the key areas for consideration is your painters process. If they are using a similar high heat oven to cure the paint, you may inadvertently incur degassing of the part. This would happen when your painters oven temp/time exceeds that where the original part was molded and painted - and it does happen, as the OE process does have variability in time/temp and there is no way to know the exactly parameters where under which you specific part was mf'd and subsequently painted. You'll know if/when you exceed the time/temp as you will see the small bubbles described above.

A shortcut might be to have the painter look at some lower temp processes where part integrity is not compromised (<120F). Another suggestion might be to contact someone like the GT Guys who have significant experience with refinishing GT parts. I don't know what they using (paint or process) but the quality of the finish paint work out of their shop is comparable to OE.

 

[Sinovac]

I was going to say all of that Rex, but I didn't want to show off.

 

[Cobrar]

I always wanted to be an attorney, but I chose death by automotive.....

 

[Xcentric]

Lots of degassing going on here.

Rex, that post is one more reason why this is the coolest forum in existence.

 

[Sinovac]

Rex, that post is one more reason why this is the coolest forum in existence.

Yes it is.

 

[SMOKDU]

The 'heat' from the exhaust flame (unburnt fuel on decel?) is likely just oxidation of the adjacent painted surface and would NOT be comparable to a bake oven where the part is subjected to a continuous level of high heat over time. 1st step is to ensure that physical part damage has not occurred to your rear fasica. You can tell if there is physical damage - e.g. part has distorted/warped or the surface has very small bubbles in the part surface (degassed).

The original front and rear GT fascias were molded, then shipped to an intermediate supplier who painted them with a red spot primer and then hand sanded. Fascias were then painted along with the car to gain color match, but were placed on separate racks, so that the fascias could be fully supported. If the fascias were not fully supported in the bake process, the high temp environment (+275F) may cause the parts to incur deflection/distortion.

As to painting, or OE repair, one of the key areas for consideration is your painters process. If they are using a similar high heat oven to cure the paint, you may inadvertently incur degassing of the part. This would happen when your painters oven temp/time exceeds that where the original part was molded and painted - and it does happen, as the OE process does have variability in time/temp and there is no way to know the exactly parameters where under which you specific part was mf'd and subsequently painted. You'll know if/when you exceed the time/temp as you will see the small bubbles described above.

A shortcut might be to have the painter look at some lower temp processes where part integrity is not compromised (<120F). Another suggestion might be to contact someone like the GT Guys who have significant experience with refinishing GT parts. I don't know what they using (paint or process) but the quality of the finish paint work out of their shop is comparable to OE.

So what you are saying is just paint it the same color as my car:biggrin