To Seal or not ?

El Toro

Member
My paint rep told me that he and his dad who has a very good collision shop never seal new oem or aftermarket parts just base over on 600 grit with Diamont base and in 10 years never had a problem. He will not recommend this but that's what works for them. I know we have talked about this before. What do you think or do? I do seal these parts.
 
A lot of production shops do base over ecoat but maybe 2-5% of them, if you want to tell me they never have extreme stone chip problems ( the reason most shops stop doing this)
I'm sorry but it defies a chemistry facts and I'm not buying it.

Then again let me be totally honest.
If they used a urethane sealer over the ecoat, like majority it would be 200% better and stronger.
If they used an epoxy as a sealer most production shops don't because of wait time, until they start have chipping problems but i would guess a 400% improvement minimum.
 
Most small shops around me do that, I don't. You can tell sometimes by the size and quantity of stone chips that sealer hasn't been used. Another reason why I stick with sealer, is that covering black (sometimes the ecoat isn't black) when you have a light color could take more time and coats that when done correctly. Color can also be off because of a bad ground coat in a situation where the part is painted separate from the car (bumpers).
 
Here in stone chip country it would be fatal to a shop's reputation to paint over e-coat. The reason it's gotten away with is probably because they are in an area with very little in the way of rocks and sand on the roads. For example, southern cities where it never snows have very clean roads, and vehicles there don't suffer rock chip and broken windshields like northern areas.
 
Always keep in mind particularly when a business says that they've never had a problem doing something you would even question that they just may have never seen or heard back about a much later in the future bad side effect of not doing something a better way.
 
Yes I feel the same way and will always seal new or aftermarket parts. This paint rep does do great work but I don't want to chance it and have it bite me later. oh we are in southern Pa. just north of Baltimore Md.
 
I don't ever consider myself an expert but I have been painting nearly 5-6 days a week for 30 years. Diamont came out with BCH2 base coat hardener to reduce what they called rock chip migration and better adhesion because at the time all of the Diamont sealers worry very sorry. Meaning a rock chip exposes the base on the edges and the rock chip will get larger and larger. If you want your refinish to last much longer and be more durable. Seal it. What I don't like is every layer of a refinish adds texture so I find sealed paint jobs are not as slick as unsealed. There are ways around that too but more time and time is money. Just my .02, as if it is worth that at times...
 
Sealer does add texture, that's the elephant in the room. I guess a "painter's painter" can lay it down like glass, but even then there is an extra layer of material that needs to shrink as it gives up solvent, resulting in at least a small loss of gloss. The best sealed jobs we end up doing are when the new e-coated part goes on a vehicle that has clear coated jambs, in which case I will just go ahead and seal, base and clear the whole part prior to installation on the vehicle. The magic happens when this cleared finish is sanded flat and the exterior based and cleared again on jobs that need it for color consistency. The second time, very little base is needed so the clear lays smooth and shrinkage is minimal. Probably what makes it work is there is usually at least a couple days between the jambing and repainting. I wish I could do them all that way!
 
I will use the SPI or U-tech sealer on collision or SPI epoxy on high end work as a sealer. Now another question do you guys seal used parts that have nice original paint before base coat?
 
I will use the SPI or U-tech sealer on collision or SPI epoxy on high end work as a sealer. Now another question do you guys seal used parts that have nice original paint before base coat?
It's not technically necessary, although most used parts have little damages all over that often make at least partial priming the best way to go. As always the intended result has to be kept in mind. A daily driver might get by with some putty and some spot priming, something nice might need to be stripped and primed complete. Part quality also plays a part, if you are working on something old that has been redone, any used part will need to be stripped and primed. With a more modern vehicle, this should not be necessary.
 
If you are doing quick collision then spray over properly prepped factory paint. If it has been repainted, reject the part, that's what I do. If it is high end and needs to be the best you can do, then always strip to bare metal, SPI epoxy and build from there. Your paint job is like a house or anything else, it is only as good as the foundation. Again, my opinion.
 
How about sealing and then sanding smooth the next day or several days later...are you still getting the benefits of sealer as long as you stay in the 7-day window? This would reduce the amount of trapped solvent, sand out any nibs and be certain that it's flat, because now it's sanded. I guess the question is then to sand or not sand the sealer? any differences in adhesion?
 
How about sealing and then sanding smooth the next day or several days later...are you still getting the benefits of sealer as long as you stay in the 7-day window? This would reduce the amount of trapped solvent, sand out any nibs and be certain that it's flat, because now it's sanded. I guess the question is then to sand or not sand the sealer? any differences in adhesion?
It's a great plan if you have the time, also there must be enough sealer build to allow for sanding. Usually this procedure only allows for a denib and a texture reduction, not elimination, to reduce the risk of sand-throughs.
 
I've done it on high end work, 2 medium coats of epoxy, and an interface pad on a d/a with 600 and then a blowing and tack rag and it's ready for base coat.
 
I've done it on high end work, 2 medium coats of epoxy, and an interface pad on a d/a with 600 and then a blowing and tack rag and it's ready for base coat.
My bad, I thought you were asking it as a question, and not a how-to statement. Certainly 2 coats of sealer could make it work, kudos to your steady hand on the sander! :)
 
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