[SEL] RE: Paint and primer

[Curt]

Andy Glines wrote:

>>
>> I have heard that clear shellac can be used as an inexpensive sealer 
>> before painting. Any body had any experience with that?
>
>
> That depends on the kind of paint that you will be putting on top of 
> it.  The PPG Delstar that I use would probably lift if applied over a 
> shellac.  I suspect that the popular Dupont Imron will have the same 
> problem.  Just follow the directions that come with the paint.  Makers 
> like Dupont and PPG have very thorough instructions that tell you what 
> you can & can't paint over.  In general, the more expensive the paint 
> the more particular it is about the surface it will be applied to.  
> You do not have to use very expensive epoxy primers to get good 
> results for your top coat.  I typically use a rather generic lower 
> cost gray primer on my stuff.  Available a automotive paint and supply 
> stores.  I also use the cheap lacquer thinner for the primer and for 
> clean up.

Andy,
Like the shellac, any solvent based primer is going to lift even under 
the best 2 part top coats if a solvent like gasoline spends much time on 
the paint. For years I used lacquer based primer surfacers on both 
automotive finishes and engines. These were top coated with Dupont 
Imron. This combination works fine on automobile finishes because you 
rarely have scratches/chips combined with the presence of gasoline. On 
engines it is a different story. This is why I have finally made the 
switch to 2 part primers. This way the primer is as inert to the 
gasoline as is the top coat. Nothing other than sand blasting will lift 
the paint on an engine/tractor painted with 2 part primer and then 2 
part color coat.
Curt Holland
Gastonia, NC