POR-15 base coat?

[Porsche-O-Phile]

POR Products now makes a sandable primer that is intended for use over their POR-15 product. My thought was to eventually redo my car using POR-15 as the base coat, their primer and paint over that. Has anyone used this type of setup? I figure anything that can be done to inhibit/prevent rust formation is a good thing.

[David]

I'm curious about what is the best primer? Maybe a thread on the attributes of each would help.

My car's been repainted twice. When I bought it 4 years ago it looked great. Now it's bubbling all over and I suspect the primer.

I just had the hood repainted because the paint peel off when I removed DE numbers (kind of stupid on my part but not unexpected.) I had them put an epoxy primer on it.

[mb911]

not a big fan of POR products I would not use it as a primer for sure you are better off with a nice dupont or ppg buildable sandable..

[berettafan]

i don't think it's wise to spray POR (sets up with humidity, which our lungs have, per my reading). most experienced paint/body guys that post on the forums seem to prefer an epoxy primer.

[klaucke]

Paint and body work often seems to be a black art, and products of choice are defended intensely on every side. That said, last time I painted a car I tried to talk to a lot of people in the industry, and the consensus I came away with was a base sealer coat of exopy primer (i.e. PPG DP-40 or DP-40LF, thinned to serve as a seal coat). Body work is recommended by PPG to be applied over this, although a lot of professionals I spoke with still prefer to put those fillers on bare metal. Then, after the seal coat (and perhaps fillers) you can apply your high build, sandable primer. From my experience, those lay down nice and you can cover a lot of imperfections with them. Then it's just wetsand and topcoat!

Per many users here, POR seems to make some great products for certain applications, but an epoxy primer like DP-40 is *really* tough. A DA sander w/ 320 won't begin to remove the stuff. After either POR or a seal coat, a high build primer seems to be a requisite step. If you have true bare metal w/ a good seal coat, you won't have to worry about corrosion.

[Fleming]

As far as I know Por-15 and Epoxy Primer are intended for two different applications.

Por15 is used inside the wheel wells, the under pan, inside the trunk, floors under the carpet, inside the doors and some of those areas "might" be finished in a top coat but most will be covered in a body shutz. The epoxy primer and top coats are about the finished top coats (fenders, doors, roof and hoods) the shine'y parts.

Asking about Por-15 it's Tie-Coat, a primer with a finish paint for the top side of the car is real close to "fingernails on the blackboard" to anybody who paints cars, because Por 15 is considered a brush on coating not visible from the outside. (Or am I all wrong on that?).

Bob

[BGCarrera32]

You really don't want to mix and match paint systems; the chemistry is complex enough that you run the risk of incompatibility when changing paint manufacturers and systems. Certain products are designed to bond together- like DP primers from PPG are formulated such that PPG DBU base coat bonds readily to it.

If the surface is properly prepared and cleaned, DPLF should take care of it. Using a line like PPG or Glasurit will afford you the largest selection of products and colors. Not saying POR-15 products are bad per-say, but on a job as large as a whole car why not stick with the experts?

[RoninLB]

i've been into this stuff for awhile.

I think DP40 is great and can be used with just about any mfg top coat. I'll be using it next summer.

I also think Por-15 is a different animal. I wouldn't use Por on a whole body unless there was no way out of it.

I once had a camaro that had a roof like rusty Swiss cheese. It was the early days when that anti rust milk you see around at auto shops for $5-8, not body shops, first came out. Maybe 15-20 yrs ago? I used about 10 bottles covering only the roof. Then primer, then acrylic urethane. Lasted 8 yrs with no bubbles then I sold the car.

I like Por painted on w/2 fairly thin coats. I've paint gunned suspension pieces and it's held up pretty good. Touch ups are easy. An opposite situation was with my factory coated wheel wells.


There are some great body treatments around without having to use Por. Aircraft supply is a good source for the best and maybe the most expensive.

[scottbooth]

I like Por painted on w/2 fairly thin coats. I've paint gunned suspension pieces and it's held up pretty good. Touch ups are easy. An opposite situation was with my factory coated wheel wells.

Do you think the problem was that POR15 won't stick to the factory undercoat?

I have stripped the undercoat and PVC from the inside of my wheel wells and was planning to POR15 them. Do you have other recommendations? (I have also stripped, and also plan to re-coat, the rest of the underside of the body.)

Thanks
Scott

[RoninLB]

how about the factory undercoating?

Then you need some kind of cheap applicator to use as an air gun. It was covered a couple of years ago. I think correct spelling is Wurth when searching.

[Porsche-O-Phile]

Yea, the tie-coat primer is what I was thinking of.

http://www.por15.com/prodinfo.asp?grp=TC&dept=3

[VINMAN]

This is the epoxy primer I've been using for years.

[MichiganMat]

POR-15 also makes a 2-part top-coat which I used on my project. Its tough stuff.

[Porsche-O-Phile]

It'd be nice if they could color-match it but it unfortunately doesn't look like it. No idea how close those colors are to factory P-car spec. Probably not close enough.

Any other "mixable" epoxy top coats you know of?

[VINMAN]

Most primers can be tinted close to the color of the top coat. Are you lookin for a primer to seal the old finish, or a surfacing primer between the sealer and the finish coat?

[Porsche-O-Phile]

The latter. I'm wondering if you can strip the panels down to the metal, coat with POR-15 to inhibit any rust formation, prime over that and use a top coat of the color desired. It looks like it can be done, my biggest issues would be adhesion between the epoxy-based POR-15 and the primer, although I suspect if they're making the primer specifically intended for that purpose, it would probably work well.

I'm not going to paint over anything that's on there now (God only knows what it is, it's 30+ years old), everything will be stripped to metal.

[mb911]

I guess Using both traditional buildable sandable/and or epoxy primers the also using por-15 I would never trust the adheasive capability of POR.. I would think your better off with a zinc-chromate primer if you are concerned with rust.. It is an avaition primer used since the 30's but again I prefer the more traditional approach as I have been less then inpressed with por-15

[Kroggers]

This is what I did on the base of my car - I know Ben will not be happy, as it is Por15, but I think the end result is good...

1) Remove all old crap and treat rust, followed by the usual Por cleaning products...


2) First layer of Por15 in silver (better to see you have a good covering)


3) Second layer of Por in black (again, better to see that you have a good cover)


4) Covered with Por primer (formulated to go onto Por15), and completed with matching red paint.


I think it ended up good...

[mb911]

for underbody I think you are fine it is when your at speed and get caught in a storm and the paint comes off in sheets that would worry me for the nice finish work

[Porsche-O-Phile]

That's my fear - that there would be adhesion problems. Anyone have some specific first-hand experience or quantitative data regarding adhesion properties of paints to the POR primer (or the POR primer to the underlying POR-15)?