Hello All,
I would like some input in regards to clearing over old paint.

1) The clear coat on our 2013 Escalade (black) is very thin on one area of the hood. I don't think it is down to the base coat yet but I cannot say for sure without sanding on it. There is no flaking of the clear coat whatsoever. It just looks like what years of buffing or aggressive buffing can do to clear coat that is thinning from UV damage already. We have owned it for two years and it has just begun to degrade enough to reveal itself.

Do you think it could just be lightly sanded and then a new coat of clear applied to it? What grit sandpaper would you recommend using?

2) The clear coat on my supervisors 2012 Sequoia (black) is flaking off very badly on his hood. I'd say about 40% of the clear coat is completely gone from the hood with the rest flaking. The base coat surprisingly looks to be in excellent shape although I haven't thoroughly studied it. I just haven't noticed any pitting or rust. Half of the clear has already flaked off with the remaining half in the process of flaking off.

Is it possible to sand this also and then apply a fresh clear coat? This would seem very difficult because you'd have to remove all of the flaking clear coat and then sand the rest without damaging the base coat. I don't see how you could sand it completely flat without damaging the base coat though; minus applying several coats of clear and sanding between each coat? In addition, what guarantee would you have that any of the original and remaining clear coat doesn't continue to peel thus ruining your new clear coat?

The hood on his SUV would seem to be a complete redo (bc/cc) to me unless y'all can convince me sanding and clearing is possible. Your input is appreciated.

God Bless,
Ralph

first what is thinning and UV damage what's it look like? is the finish going flat or dull looking ?
Jay D.

badsix wrote:first what is thinning and UV damage what's it look like? is the finish going flat or dull looking ?
Jay D.

Hello Jay.
I am talking about the clear coat getting thin and yes causing some minor dulling to occur. The clear coat on a vehicle will degrade with age from UV damage and/or neglect and/or abuse.

I was a professional detailer for 14 years so it's something I can recognize. It's to the point that I wouldn't want to put a buffer on it because I wouldn't want to degrade the clear coat any further at this time.

I am painting our BMW for my daughter already so I could just buy extra clear and apply it to the Escalade. There doesn't appear to be any degradation of the base coat at the moment but only wet sanding could truly reveal that.

My question is would applying more clear suffice or would you professional painters elect to apply a bc and cc?

Thanks,
Ralph

Ralph_III wrote:Do you think it could just be lightly sanded and then a new coat of clear applied to it?

No. If it looks different then it's already failed. It would be pointless to just rub back and paint over it. An unsound substrate will still fail and take that nice new paint on top with it.

Ralph_III wrote:What grit sandpaper would you recommend using?

P40.

Ralph_III wrote:The base coat surprisingly looks to be in excellent shape

It's not. Once exposed the base coat is ruined. Remove all and respray.

sorry, that's the correct way to do it.

PIcs please

NFT5 wrote:

Ralph_III wrote:Do you think it could just be lightly sanded and then a new coat of clear applied to it?

No. If it looks different then it's already failed. It would be pointless to just rub back and paint over it. An unsound substrate will still fail and take that nice new paint on top with it.

Ralph_III wrote:What grit sandpaper would you recommend using?

P40.

Ralph_III wrote:The base coat surprisingly looks to be in excellent shape

It's not. Once exposed the base coat is ruined. Remove all and respray.

I disagree with the last part. If the base is in good shape you can scuff it and put some adhesion promoter on before reclearing.

Ralph_III wrote:Hello All,
I would like some input in regards to clearing over old paint.

1) The clear coat on our 2013 Escalade (black) is very thin on one area of the hood. I don't think it is down to the base coat yet but I cannot say for sure without sanding on it. There is no flaking of the clear coat whatsoever. It just looks like what years of buffing or aggressive buffing can do to clear coat that is thinning from UV damage already. We have owned it for two years and it has just begun to degrade enough to reveal itself.

Do you think it could just be lightly sanded and then a new coat of clear applied to it? What grit sandpaper would you recommend using?

Im not sure how much experience you actually have at autobody/paint so I will assume no shop experience. If you have some experience just scuff the area where the clear is thinning and reclear it and shoot some blender where the edges overlap. Then rub it all out and youre good. Personally this is what I would do. Then i would immediately sell the damned thing.

COULD you sand the whole hood and re clear it? Of course you can. The sandpaper you want to use depends on how much time you want the job to take. I would start with 320 (on a DA not by hand) and work up to 600.

It is very important that you sand evenly meaning the final finish should be totally uniform before reclearing.

To do this requires practice but i can tell you the basic idea. Put tape on substrate equal to a 2x2foot square. Sand (with 320 ON A DA NOT BY HAND) until the finish looks even to you, then spray some water on the section and squeegee it off. If you dont have a squeegee go buy one theyre cheap and highly effective. Basically once the water dries look at the section you sanded. You will probably see lots of grayish whitish with patches of black (i think you said its black) showing you where you need to sand more. You should also see shiny specs all over the place, those need to be sanded down more. You want the section to be uniform in appearance.

As putting new paint over old is a no no you will need to be concerned with adhesion. Typically new over old the new paint sits on top of the old and will fail in spectacular fashion. To avoid this your sanding and removal of contaminants must be precise. After sanding down to 600 grit (the bulk of the work is done with 320 from there hit 400 and 600 to remove the 320 scratches) hit the entire panel especially the edges and any hard to hit spots with a GRAY scuff pad. From a paint supplier not oreilleys. You can use a gold pad but its gonna take a while. A red scuff pad can be used to save time but you cant put clear or base over the scratchea youll want to hit the panel with a gray pad lightly or a super assilex pad if you have one.

After scuffing is done and the appearance is UNIFORM proceed to wax and grease. Take your time amateurs are always in a rush and auto paint is unforgiving.

Wet a section maybe 4x4foot max and quickly dry with a clean towel. Wear gloves. Never let wax and grease dry on the substrate. If that happens just wax and grease that area again and dry it correctly.

I recommend spray a light coat ONE light coat of adhesion promoter before reclearing.

You asked can it be done, yes.

Should you?

No.

Along with difficulties getting the new clear to bond with the old you are also going to run into problems getting the new clear to look correct once it dries. I am not talking about texture i am talking about what we in the trade refer to as "factory orange peel" or in laymans terms the thickness of your clear.

If you must take your shortcut I told you what you need to do. I would put 4 coats of clear on so you have something to bite into and shape to desired thickness and dimensions. Black is especially unforgiving your eyes will be instantly drawn to inconsistencies and blemishes.

Personally and from experience just buy some sandable primer, sealer (unsandable primer), base and clear and sand the old clear and base down then reapply. The advantage to doing this well there are many but the one thats going to save you the most time and money is that by doing the job properly you will be able to sand all the panel till its nice and tight. I dont know how to put this into words. If you go with your shortcut i imagine the end result will look a bit bloofy or distorted rather than have that tight look like the metal is black rather than
metal painted black.

2) The clear coat on my supervisors 2012 Sequoia (black) is flaking off very badly on his hood. I'd say about 40% of the clear coat is completely gone from the hood with the rest flaking. The base coat surprisingly looks to be in excellent shape although I haven't thoroughly studied it. I just haven't noticed any pitting or rust. Half of the clear has already flaked off with the remaining half in the process of flaking off.

Is it possible to sand this also and then apply a fresh clear coat? This would seem very difficult because you'd have to remove all of the flaking clear coat and then sand the rest without damaging the base coat. I don't see how you could sand it completely flat without damaging the base coat though; minus applying several coats of clear and sanding between each coat? In addition, what guarantee would you have that any of the original and remaining clear coat doesn't continue to peel thus ruining your new clear coat?

The hood on his SUV would seem to be a complete redo (bc/cc) to me unless y'all can convince me sanding and clearing is possible. Your input is appreciated.

God Bless,
Ralph

Same rules apply as per my comments above. As for removing the flaking clear hit it with compressed air. Shop air not a pancake compressor air. Go alobg all the flaking edges until you either blow off all the old clear (ha! In your dreams) or you end up with islands of clear here and there still stubbornly adhering.

Unfortunately the islands of clear are going to have to be feathered out. You are going to eat into your base doing this so get some paint. If you shoot base or clear over old base or clear remember scuff it good with gray scuff pad and a light coat of adhesion promoter before spraying.

Personallygo ham on the damned thing and re base and clear the entire hood. You will be hating life otherwise.

Methyl Mike wrote:

NFT5 wrote:
It's not. Once exposed the base coat is ruined. Remove all and respray.

I disagree with the last part. If the base is in good shape you can scuff it and put some adhesion promoter on before reclearing.

You can disagree, if you like, but that doesn't change the fact that base coat, once exposed, will never be any good again and will look different if recleared. Not to mention that clear will not adhere to it.

Adhesion promoter is designed for use on raw plastic, not over painted surfaces. There were some people who recommended use of AP as a wet bed, to aid in metallic blending. While it worked it's not a recommended practice and there are much better wet bed solutions. Some adhesion promoters now include a fine metallic so the product is no longer clear - partly to discourage improper use and partly to enable visual assessment of coverage.

As for your other solutions, apart from removing the old paint and starting afresh, these really are poor recommendations that will lead to a sub-standard job.

and for painting over degraded clear, the reason I ask if the clear was dulling or going flat that's a sign it failed. your idea of blowing it off was a good one, but you stopped there with your recommendation to sand and reclear what didn't blow off. this is just bad information and a bad way to repair that panel. I believe we here like to strive for a little closer quality. you sound like you got your painting education from Smiling Sam's used car lot. ( make it look good as cheep and quick as you can) trust me I worked for one when I was a kid and I've see it all.
Jay D.