Sealer absolutely necessary?

R

RAC65

Can you go from epoxy to 2k to base or is the epoxy over the 2k a must? I am not sure if I have enough material on hand and my present financial situation will not allow me to buy more.
 
The 2k (urethane primer) will need to be sanded after it cures. You can base after that without sealing. use the right grit.
 
Thanks Bondoskimmer. What are the advantages to painting over the sealer versus painting over the sanded 2k?
 
there are so many advantages to using epoxy sealer. adhesion , color hold out , helping to limit shrinkage but most of all the peace of mind that you wont have a major redo down the line , i would put off painting until i could afford some epoxy .
 
shine;24777 said:
there are so many advantages to using epoxy sealer. adhesion , color hold out , helping to limit shrinkage but most of all the peace of mind that you wont have a major redo down the line , i would put off painting until i could afford some epoxy .
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I agree with the above....you must use a sealer....period
 
Thanks guys. Should you always use a reduced coat or is it ok to just mix it one to one like normal. Does the reduced epoxy lay down a little smoother?
 
A coat of reduced epoxy sealer isn't any harder to apply than the first coat of base or paint, in fact easier to put on in my opinion compared to some top coats. So why not do it for the benefits it provides. I used to use sealers years back only on "problem" surfaces. Now that I use the SPI epoxy I use it almost every time.
 
If my urethane primer is good and the color will cover ok then I never seal. No problems ever. Ever.
 
Bondoskimmer;24820 said:
If my urethane primer is good and the color will cover ok then I never seal. No problems ever. Ever.
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I have done the same over urethane primer with no problems. I think if it's over epoxy that's full cured, 6-7 days, top coats will have better adhesion on a fresh coat of epoxy.
 
Missing the point here. Your paint IS NOT going to fail if you don't use epoxy or urethane sealer. It isn't going to fly off going down the road. It isn't going to peel off a year later.

But it is just a fact that a sealer improves the adhesion of the base to the substrate. The base is the weakest link in the whole proccess. You take 2 bumpers prepared in the same manner. One you 2k primer, sand and paint without a sealer. The other you use sealer (choose epoxy or urethane). I'm sorry but the one with sealer is going to resist rock chips and other things better than the one without sealer. Top it off with activating the base and it is as good as it gets.

Doesn't mean NOT using sealer is wrong. It is taught that way every day and wrote that way in all the manufacturer tech sheets. But remember those sheets are written primarily for production work....
 
I understand and respect what you say jeremy. I am ok with either but when asked I speak from my personal experience. Some from my own vehicles. Namely a Honda front bumper I shot as I described (urethane only) 7 yrs ago. No epoxy period and it has 100,000 plus mi on the front bumper. Still good.

The epoxy sealer point of view does make perfect sense to me as you have explained it. I just am not compelled to shoot sealer every time b4 my color goes on.
 
I don't shoot sealer every single time either.

Thing is most guys here are diy and want the best overall job possible. When you look at it that way I just don't see a reason NOT to use sealer...especially on a restoration.

Its all good either way
 
I put epoxy on bare metal faithfully. Occasionally etch on galvanized but nine out of ten it is epoxy for me to seal bare metal..
 
I agree that epoxy sealer makes for the best adhesion and chip resistance.

But virtually no collision repair shop uses sealer on a regular basis, except for jambing and painting of new e-coated parts. Sealer in a repair and blend environment can easily make more mess than it's worth, unless it's transparent. For example, if you are painting the vehicle when assembled, and have taped off the jambs, sealer will get into the jambs and not be completely covered by color due to Murphy's law.

For sealer to be used in the proper way, the part(s) should be either painted off the vehicle, or concurrently with the jambs.
 
This turned into a very good discussion about sealers. But it's in the "primer" section of the forum. I guess it would show up if someone used "sealer" in a search.
 
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