Is A Sealer Needed Over Primer?

[oldcarfan]

I was at the auto parts store buying a can of sandable primer and the guy asked if I used a sealer between the primer and the paint. I haven't but now I'm wondering if I should. I normally use Duplicolor sandable primer under any type of paint with no issues, so what does the sealer do? It says it gives an improved gloss. Any thoughts?

[rattle can man]

Sealer is something you might consider if painting colored plastic. Colors from the plastic can bleed through paint. I've had orange colored plastic bleed through the when I applied a tiny spot of Mr White ton top of the primer. 

[Shark]

Maybe if you did a ton of body work that might ghost thru when using a hotter paint. I tend not to use a sealer. A lacquer silver acts as a sealer for plastic color bleed thru.

[StevenGuthmiller]

I use that exact “primer sealer” all of the time in place of the sandable primer, or in conjunction with it.

 

 

Steve

[Dave G.]

Think of sandable primer as porous and the sealer as a shell coat or barrier coat over the primer.

There are also primer/sealers. Not sure about that in the Duplicolor lineup. 

[Muncie]

I'm with Steve and Dave - especially if any of the top coats are lacquer or other materials that may harm plastic. 

In order of body and bodywork, primer, sealer, then finish top coats. 

The Dupli Color primer sealer 1699 sprays thin and it may need multiple coats to keep trouble underneath.  It sprays smooth enough that it won't need sanding. (I would discourage sanding because it may open the barrier and let top coat harm the filler or plastic underneath.)

A good sealer is cheap insurance with no downside.

[Mark]

You don't want to sand that sealer primer.  Doing so "opens it up", the top coat will likely raise sanding scratches in that area.

Anything I use lacquer paint on gets a quick blast of sealer primer.  The sprays seem to have less "solids" and more "carrier" (reducer) lately, making the paint thinner and needing more of it to cover.  The sealer helps reduce the possibility of scratches or imperfections showing through the primer.