Sealer/primer sealer

General Discussion. Make yourself at home...read, ask and answer!



Settled In
Posts: 68
Joined: Sun May 15, 2016 3:33 pm

Country:
Canada
PostPosted: Sat Apr 06, 2019 5:30 pm
I'm having a hard time understanding why you would add a Urethane sealer over Urethane primer and what the benefits would be. In my case I have several layers of Urethane high build primer on the car and all surfaces have been wet sanded with 600, by adding 10% reducer I can turn that same primer into a sealer. But really it is just a thinner layer of same compound, how can it seal any better than what is already on the car, what am I missing?
I'm not looking for ways to get out of extra work or anything, I'm just try to figure out the logical argument for it.
Thanks

User avatar

Board Moderator
Posts: 9878
Joined: Fri Oct 20, 2006 12:40 pm
Location: ARIZONA
PostPosted: Sat Apr 06, 2019 8:52 pm
Sealer is optional unless you are using one of the new paints that require a tinted sealer first.

If your primer has been properly sanded and prepared it will not be a problem going directly to color. Sometimes after block sanding the primer the car has a few different shades of color to it. This isn't a problem if you are shooting enough coats of color to cover a black and white spray out board. Shooting a sealer coat however will give you a consistent color to paint over.
1968 Coronet R/T


ACTS 16:31



Settled In
Posts: 68
Joined: Sun May 15, 2016 3:33 pm

Country:
Canada
PostPosted: Sun Apr 07, 2019 5:40 pm
Thanks, that makes perfect sense, luckily I used nothing but grey epoxy and primer so the car looks uniform all over.

User avatar

Top Contributor
Posts: 1745
Joined: Tue Apr 26, 2016 6:53 pm
Location: Denver, CO
Country:
USA
PostPosted: Tue Apr 09, 2019 7:08 pm
Sealer promotes better adhesion, than spraying base straight over sanded primer.
also so many shades of gray it is usually cheaper to use gray shade sealers than 4-5 coats of base,

urethane sealer (better adhesion that basecoat, also will get better coverage if use proper shade gray)
basecoat w/ 5% hardener (this will allow cross linking with the sealer to form a better bond)
clear ( this will cross link with the basecoat)

its not very good practice to base straight over sanded primer
Experienced Trained Certified

SATA Spray Equipment Germany
Axalta ChromaBase Elite Standox Imron 5000 6000
PPG Delfeet Deltron Global Matthews
Sherwin Williams Ultra 7000 Genesis
Valspar DeBeer LIC
Akzo Nobel Sikkens Lesonal



Settled In
Posts: 68
Joined: Sun May 15, 2016 3:33 pm

Country:
Canada
PostPosted: Thu Apr 11, 2019 6:03 pm
Painter Dave,
The primer is now very smooth and consistent, not because of my spraying technique but because I spent so much time guide coat sanding, if my application of sealer isn't perfect the first time I'm sure I will end up with some areas of orange peel or possible runs. Then I'm right back to wet sanding again and no farther ahead than I am right now.
I don't doubt yours is good advise but unless adding that 10% reducer to the urethane primer is going to make it flow out consistently I'm sure I will have to sand again.

User avatar

Board Moderator
Posts: 9878
Joined: Fri Oct 20, 2006 12:40 pm
Location: ARIZONA
PostPosted: Thu Apr 11, 2019 7:34 pm
Reducing the primer will make it thinner and thus easier to get it to lay down.
If you are getting a lot of orange peel then you either don't have the gun adjusted properly or you are too far away from the panel.

Tape some masking paper on your wall. Before you fill the gun, back your fluid knob out until you can pull the trigger full open. While holding it full open turn the fluid knob back in until you feel it lifting the trigger. Release the trigger and turn the fluid knob in 1/2 turn more.

Now hold the trigger full open and set your PSI at the gun. Put your mixed paint in the gun and hold it no more than 6" from the paper. Squeeze the trigger full open for one second. I say 1/1000 and let go. You should see a nice full cigar shaped pattern with no runs or blank spots. If you see runs, turn the fluid knob in another 1/2 turn. Be sure to check your PSI at the gun and try it again. You can also increase the air pressure to make the droplets finer.
1968 Coronet R/T


ACTS 16:31



Settled In
Posts: 68
Joined: Sun May 15, 2016 3:33 pm

Country:
Canada
PostPosted: Sun Apr 14, 2019 10:02 am
So I sprayed the sealer yesterday, some success but lots of cats tongue and some areas orange peel. 68 Coronet R/T, I did those adjustments to the gun and it helped a lot but my spraying technique needs lots of work, juggling pass speed and height is tough.
So instead of sanding down to blemish free with wet 600, I took off 60-70% of the cats tongue and peel peaks leaving some of the pits/valleys so there will be some tooth left for the paint to grab on to, is that allowed?

You'll see from the photos that the overall surface is flat and smooth and with 3-4 coats of clear I will be able to get a wave free highly reflective surface but the real question is
when you look deep in to the paint will those pits/valleys still be visible?
Thanks
IMG_1592 (1024x768).jpg

IMG_1595 (1024x768).jpg

IMG_1589 (1024x768).jpg

Return to Body and Paint

Who is online

Users browsing this forum: Drew and 101 guests