Mount new parts for paint OR not...?

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PostPosted: Sat May 20, 2023 9:35 am
So I am wondering how everyone feels about the topic of new part installation and paint. Say in terms of NEW doors, fenders, hoods, bumpers etc and under the premise of replacing with new e-coated, new-to-you already finish painted, and new-to-you needs minor work still before painting.

I as because I just recently acquired an excellent condition tahoe fender for dirt and then went and slid it right off a table onto the asphalt trying to get the plastic wheel housing off BUMMER...

So what are the pros and cons my prime concern being NEW and E-COATED. I feel like that is not enough protection to mount and paint with just the black dip coat. Perhaps I am wrong and thats the best most adhered coat on the car? Then there is still the issue of door jamb. Due to fear of damaging another fender (And they are cheaply made and will dent with a single ugly stare)... But I am so terrified I will drop another one I am really tempted to bolt the new fender in place and maybe even brush the inside door jamb once mounted.. And my new expensive hood OMG gives me chills...

So how many of you body guys are terrified about damaging new parts handling them for paint prior to mounting on a vehicle?? I have a sneaking suspicion its one of the biggest "nasty subjects" in the business..

I mean I can DEF see now that I should have just immediately mounted that factory finished fender I had regardless of requiring a color change, but I am wondering about bolting down on E-coating..

OF course the pain-in-the-a subject of masking and protections play in here big time...

WHAT IS MORE IMPORTANT TO YOU. The pain of masking, or the pain of taking extreme car not to drop and damage a new part??



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PostPosted: Sat May 20, 2023 2:51 pm
id say forst find out if its actual e coat. put some lacquer thinner on a rag and wipe the fender. if any comes off, strip that crap off.
if it is e coat, id still spray epoxy primer before paint.

paint the parts off the tahoe. it will be a lot easier.

id rather be over protective with freshly painted parts,. ive never had a time i said,' i shouldnt have spent so much time protecting the part."
i have said, "%#@* im an idiot for not taping off that edge" a time or 2.
i put a blanket on the ground where id be working just in case id get the dropsies.

most important to me is getting the parts back on without damaging them- no matter what i have to do and how long it takes.

when ya go to put the new hood on, drape blankets over the engine bay and fenders.

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PostPosted: Sat May 20, 2023 9:47 pm
It's a matter of being sensible. I know that accidents do happen but get someone to help if the panel is big or awkward or heavy. Use or make stands for your panels that hold them securely - occasionally I will tie a panel to a stand if I'm not happy with security because of panel shape. Learn, by trial and error if necessary, the best ways to hang a panel on a stand - use the shapes in the panel to improve holding power.


tomsteve wrote:id say forst find out if its actual e coat. put some lacquer thinner on a rag and wipe the fender. if any comes off, strip that crap off.


I don't agree with this. E-coats come in all different types but most are dipped, rather than sprayed and that, in itself, means that they're 1K products. There are also waterborne e-coats and these, too, may come off with a wipe of thinner. It doesn't mean that they're no good.

Usually the part will come with some instruction on how to prepare for painting. Follow this exactly and you'll have no problems. Ignore it because you think you know better and you will have issues.

Usually, giving a panel a coat of epoxy, as a sealer, is fine, but again, follow the instructions.
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PostPosted: Sun May 21, 2023 8:10 am
painted one car assembled.

this one un-assembled.

much easier for a rookie to paint un-assembled (for me) and I would much rather be carefull in re-assembly than have the daunting task of the whole car. other benifits for me are if any errors your more likely to isolate it and see it before going "big" and maybe easier to stop right there and get right. also if all gos well, you wont mind extra caution knowing your handling the nice successfully painted panels.

my parts were repop e coat likely cheap china e coat, I lightly sanded them all and used epoxy primer. ive read plenty not to risk a incompatable reaction of products.
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PostPosted: Tue May 23, 2023 10:55 pm
THANK YOU for all the replies..! Just putting in some feedback. I tested the fender today (that FED EX DING'D ALL UP) with some ADVANTAGE 89 which apparently has every caustic ingredient on the planet. I was surprised with 50+ hard strokes with a bounty paper towel and not a single bit of black came off. What surprised me the most was that it was the cheaper fender and not the CAPA one. I have not tested the super expensive hood I ordered and will do soon enough on the underside, but I don't think that is coming off either (ReplaceXL) brand. I'm actually pretty impressed with these undercoats and will think long and hard before I do anything more than etch them with 800pad and clean with degreaser and tack cloth.. After doing that bleed test I honestly dont want to do anything that could jeopardize to the metal..

I honestly dont see the need for primer IMH(and ignorant)OPinion. Can anyone give me a super solid reason to use primer over these e-coats for use underneath as prep for a urethane finish coat of silver birch metallic?

I recall my experienced buddy painting and putting on the left fender in 2018. I see where he painted the inside of the fender too(my memory just fails). But I know he would not have primer over the Ecoat for the backside. Still I recall him going over it with the orbital once mounted and remember a lot of gray. Maybe it got dinged and he had to lay a bit of bondo I just dont recall. These car parts today are just garbage in terms of metal gauge..

I really thinking he was just using a super high grit on his orbital to prep in place for final base coat and the first base he shot it with while sill off the car was just blurring to grey.. I just don't recall maybe it had a small ding out of the box and he filled it forcing him to prime..

New fender should be here in a day or two. I'm not holding my breath for an undamaged one. I honestly don't think FedEx is capable of shipping a fender intact..\

If I should decide that these factory e-coats are good enough to paint over, should I just prep for base coat even higher like 1600 hand pad?? I seem to recall him using that for something.. Will 800 pad used on e-coat show thru on base coat??



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PostPosted: Thu May 25, 2023 11:15 am
BBC333 wrote:
I honestly dont see the need for primer IMH(and ignorant)OPinion. [b]Can anyone give me a super solid reason to use primer over these e-coats for use underneath as prep for a urethane finish coat of silver birch metallic?



just a greenhorn here but i couldnt ever scuff e coat without breaking through to bare steel somewhere.



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PostPosted: Thu May 25, 2023 1:14 pm
Well that may be the answer right there. But apparently I now have one dinged fender to use, and another dinged finder to experiment on. All thanks to fed Ex incompetence.

tomsteve wrote:
just a greenhorn here but i couldnt ever scuff e coat without breaking through to bare steel somewhere.


I suspect you may be right on that.. So my approach will be to test the worst of the two fenders with a scotch pad in the neighborhood of 800 grit and keeping in mind that etched is ETCHED and there is no reason to go a single stroke beyond that. Perhaps it will work, and then I'll hit it with degreaser and start firing silver birch at it. I am also concerned that 800 may be too slick for a silver birch metallic.... So my plan I think will be to go super light coats and extend the flash time a little more with each application I guess I could even start on the backside that faces the engine compartment for that matter with one I plan to use. But If it doesn't then I'll start worry about whether or not to attempt to work the high build primer I have, or just go with a lighter primer for color change. Actually while thinking right now. If I do go scratch thru on the test, or my urethane color coat wont lay down right on the etched e-coat, THEN I will run out and get some 2K in a can and go with that on the fender I will use.

Im pretty upset about the thought of having to work a part. I believe I could have pulled off a simple pad etch to color coat operation. This is complicating my plan significantly.

I'm really kind bummed out about Fed Ex damaging the fenders I order. I wouldn't even mind attempting some body work on inward dings. But this latest fender they sent (and the best one of the two) has an outward "ping" looking damage that will have to be pressed back inward and that wont be easy cause the metal is clearly STRETCHED. Id say the whole ding is about 1inch in diameter but its got a really high peak on it. The first damaged fender I received has too much minor but scattered damage to choose it. But I may be overreacting and perhaps because this metal is so thin it can be pushed right back out. We'll see. I may photo document the process. But I really suspect the only way to fix the an outward ding like this without contorting the rest of the fender would be to cut it out and backer fill it.. Just (^)^*(*&(_)(^$&^$. What is the world coming too. And now I quickly recall the perfect one I had got off that tahoe that I dropped when this all started. I should have just hung it on there green so I could just get my hood on and at least be able to move around in it while I figure things out.. BLAHHHH!!!

I almost don't care at this point as long as the paint sticks right. I'm just not laying out 3-400 bux for one of these sorry thin Tahoe fenders, CAPA or not, they all suck including the ones that came on it when brand new..

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PostPosted: Fri May 26, 2023 5:09 am
I can't understand how anyone can go through, even E-coat, when scuffing with Scotch. You just scuff the surface, not try to clean it off.

Etching is different. It's a chemical process using acid that prepares the surface. Etch primers can't usually be used under epoxy and IMHO, they should be primed before topcoating.

Some e-coats are ready for topcoating as they come from the factory. Usually these are genuine OEM parts, especially from European manufacturers. Generally grey in colour whereas others are black.

BBC333 wrote: But I really suspect the only way to fix the an outward ding like this without contorting the rest of the fender would be to cut it out and backer fill it.


I doubt it. I've seen lots of transit damaged panels and they generally not that bad. I little panel beating of some dents usually fixes them right up. Why don't you put up a photo and let the metal working gurus give their opinions?

BBC333 wrote:I almost don't care at this point as long as the paint sticks right. I'm just not laying out 3-400 bux for one of these sorry thin Tahoe fenders, CAPA or not, they all suck including the ones that came on it when brand new..


The paint will stick just fine if you follow the correct procedures. As for thin panels there are many good reasons why panels are thinner than they used to be.Firstly strength. HSLA steels are way stronger than they stuff that they used to use - which was thick because that was the only way they could give it any strength. Of course, working it was like beating lead.

And talking of lead, that's the next good reason. Thinner panels, made of much stronger steel are lighter. Today I filled up my car. Diesel was just under $2/litre and at that kind of pricing I'm glad that my car probably weighs 3/4 of a tonne less that it would if if had been manufactured using old technology steel.

Thirdly, that extra strength comes with safer motoring in the event of an accident. Ever watched those videos of crash tests done on 1960's cars? Note how they just collapse. New cars have crumple zones and absorb the impact while HSLA steel provides a cocoon of strength around the passengers. I know which car I'd rather be in, in an accident. :wink:
Chris



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PostPosted: Fri May 26, 2023 7:07 am
A one inch stretched ding, is nothing to get crazy over. It is an easy fix. I've fixed brand new fenders that were damaged in shipping, or on the dealer's shelf, just so I wouldn't have to wait to get another one. About 2 minutes with hammer or slapper, and another 5 minutes to fill and sand.
Also, I've never broken through Ecoat. Use Scuff Stuff, and a gray Scotch Brite pad to clean and scuff. You're being too aggressive with it.

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