Prepping for Primer Questions

[MaxxdOut]

I’m in the process or restoring a rough 72 beetle. I manually stripped the car with 60/80grit paper on various size grinders/polishers. To protect the bare metal I choose to picklex it while I worked on the extensive metal work. Although I stripped approximately 98% of the finish to bare metal, I didn’t strip the jams, drip rails, etc as I planned to scuff those areas.

I’m currently in the process of finishing the front metal work and planned to prime it with PPG Omni MP170 (Epoxy Primer) once complete. Yesterday I thoroughly scuffed the areas that still have paint with a red scotch bright pad and then reviewed the primer tech sheet in preparation for priming within the coming days. The tech sheet states 220-320 grit on old finishes/filler and 120-180 on bare metal.

Questions:

• Will scuffing the remaining painted areas with a red scotch bright be sufficient for prepping for primer? Or should I use 220-320 paper? Or should I attempt to strip these areas to bare metal?

• I recall reading somewhere maybe on this forum that some primers negatively react with lacquer paint. The MP170 tech sheet didn’t mention this. Therefore, I assume this isn’t an issue. Out of curiosity how can someone discern if paint is or is not lacquer?

• I’m looking for a good quality non self leveling seam sealer for the rebuilt strut braces for the front of the car. Factory VW used very thick rubber type sealer. Does anyone have any recommendations on a simmilar product?

Thanks in advance for the assistance.
Chris

[Len]

Questions:

• Will scuffing the remaining painted areas with a red scotch bright be sufficient for prepping for primer? Or should I use 220-320 paper? Or should I attempt to strip these areas to bare metal?

• I recall reading somewhere maybe on this forum that some primers negatively react with lacquer paint. The MP170 tech sheet didn’t mention this. Therefore, I assume this isn’t an issue. Out of curiosity how can someone discern if paint is or is not lacquer?

• I’m looking for a good quality non self leveling seam sealer for the rebuilt strut braces for the front of the car. Factory VW used very thick rubber type sealer. Does anyone have any recommendations on a simmilar product?

Thanks in advance for the assistance.
Chris

1. As long as you do a good scuffing with the red pad you should be ok. Don't leave any shiny spots.

2. If the car has been repainted using lacquer then wetting a cloth or paper towel with thinner and wiping a spot should melt the paint. If you stripped it using sandpaper and the paper clogged up quickly then that could also be an indication of lacquer.

3. Fusor 800 series seam sealer is one of the best all-around seam sealers.

LINK

[Steve g]

Not what you asked, but looking at your pictures, here's what I would do. You've invested a lot of time in the prep and repair of most of the car, but the devil is in the details. I would take a sandblaster to those remaining areas and clean them out properly. Not so much the larger jamb area under the hood, but rather the hinges and seam areas that will be very visible and are difficult to properly prep. Trying to feather out chips in something like a door hinge is very difficult and if poorly done will be quite visible.

170 is a very good product, esp for the money. But you don't want to have to sand it, especially in the nook and crannny areas. Shoot your expoxy, let it flash off for 30 - 60 mins, then shoot at least 2 coats of the Omni SV282 2k primer surfacer. Now you're ready to start blocking. If you have further filler work to do the little bit of wasted high build you will grind off is a very worthwhile trade off for not having to thoroughly sand the entire car.

Steve g

[MaxxdOut]

Steve and Len thanks for the info.

I have always been a little afraid to hit a car with a sand blaster larger than a spot blaster. Do you have any recommendations on a blaster size that I may need? Also, what media and volume of it should I purchase?

I have heard mixed feedback on pressure and siphon style blasters.


I also need to figure out a way to keep the dust down so I don’t piss of the neighbors too bad. Any ideas?

Thanks again.
Chris

[Steve g]

There's no need to fear damage with the blaster with what you have left to do. It's large panels that you can heat and warp that are problematic, but even they can be done if you're careful. Just don't sit in one place too long. Opt to take smaller amounts off at a time. The seams and hinges are good solid pieces as are the jambs should you opt to do them. You definately want a pressure blaster. Siphon units don't work worth a damn. I've used both. The one Len sells here is perfect. Cheap and large enough to do most small to med size jobs.

Media Blaster

For what you're doing any cheap abrasive material will do, play sand being a common one.

Keeping it clean is a tough one. Don't do it outdoors. Line your shop with plastic sheeting and do small amounts at a time so as to not get too big a cloud. It doesn't look like you have much to do. Do a door and adjacent seam, let the dust settle, do another piece and so on. Blasting uses a lot of air so unless you have a very large compressor you're going to have to wait for air anyways.

Steve g