Explain it like I am 5

[mango-smoothie]

I'll just jump into this. i would like someone to please explain the steps required to go from panel replacement to two stage paint.

all my panels that required replacing are now replaced. (no need to explain welding, etc - everything was butt welded properly - i just am lacking knowledge of the steps to get to paint)

i have seam sealed the back side of the welds and fiberglass (short strand) the front, sanded and polyester filler applied. I'm about 70% done the sanding and my mind is turning to primer, sealer, etc.

obviously i am no expert, but i do consider myself competent and certainly willing to learn. I've never painted a full vehicle before and i will likely be taking this to full paint (or i might get someone to actually shoot the paint, but i am doing everything up to that)

so...

please explain what i do after the filler and rest of the body is completely sanded at 120 grit.

(i have a suction 1.4mm gun and was going to pick up a HVLP 2.3 for the primer. i have a big air tank, compressor, dryer, DA and board sander. )

thanks

[Thrasher22]

After just finishing the first and likely only car I'll ever fully paint, I'd summarize it to:

1. Block to at least 220 grit
2. Mask
3. Clean with Wax and Grease remover and tack cloth
4. Spray with high build epoxy primer
5. Block everything to 400 grit wet
6. Repeat steps 2 and 3 until satisfied (with prep step in between)
7. Paint per manufacture's specs
8. Color sand (optional)

Dry times, gun settings, number of coats will depend on the paint you select. Make sure you have a good air filter when you're spraying, and ideally a way to vent the fumes. Its pretty horrendous stuff.
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1975 Westfalia - http://www.thesamba.com/vw/forum/viewtopic.php?t=516701

[mango-smoothie]

thanks.

what about epoxy sealer between 3 and 4?

[marklaken]

Depending on products - some epoxy primers are also epoxy sealers (terminology really gets confusing with epoxy primer systems) - check into what you are using and follow the tech sheets. You may need a sealer step, you may not need it.

A couple extra notes:

1a: follow the data sheet of primers for prep grit (wax/grease/dust removal is more important than sanding grit for primer adhesion)
7a: spray sealer coat prior to topcoat
7b: block sealer coat ASAP to remove any orange peel - follow topcoat tech sheet for grit, but good to go at least 400 (go higher if possible to minimize sand scratches showing intopcoat)
7c: Apply topcoat within recoat time of sealer
8: Color sanding is not really optional

From my experience (my paint work is always heavy peel), if I don't block the sealer prior to topcoat, my color sanding will go thru topcoat to reveal sealer/primer
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Wish List:
1967 Wesfalia SO-42 Parts Needed: Kitchenette, Cot Poles

'65 rear left beetle fender

15" Bus Wheels in fair condition

Mark Laken
Fort Collins, CO

[jspbtown]

Here is my 2 cents:

1. Spray completed bodywork with an epoxy primer. Allow to dry suggested dry time, but within recoat window
2. Shoot several coats of a high build polyester primer. Let cure
3. Guide coat and block it with 400 grit (solids) or 600 grit (metalics).
4. Reduce your epoxy primer by 20% and spray as a sealer
5. Appropriate flash time
6. Shoot base coat x3 (for coverage) with appropriate flash
7. Allow for last flash (usually longer than between base coats)
8. Shoot clear x4 with appropriate flash (this will give plenty to sand)
9. Depending on peel block with anywhere from 1000 to 2000 grit
10. Buff

[Thrasher22]

[mango-smoothie]

i appreciate the replies guys

so, in summary:
1) rough metal / paint to ~80 grit to allow filler adhesion (i used a DA)

2) short-strand fiberglass over welds (and seam-sealed behind)

3) sand again (100 grit)

4) apply quality polyester filler

5) sand again (100 grit)

6) follow the data sheet of primers for prep grit (wax/grease/dust removal is more important than sanding grit for primer adhesion)

7) Mask (and wet floor to keep dust down)

8 ) Clean with Wax and Grease remover and tack cloth

9) Spray with high build epoxy primer

10) Block everything to 400 grit wet

11) Repeat steps 9 and 10 until satisfied (with prep step in between)

12) spray sealer coat prior to topcoat

13) block sealer coat ASAP to remove any orange peel - follow topcoat tech sheet for grit, but good to go at least 400 (go higher if possible to minimize sand scratches showing in topcoat)

14) Apply topcoat within re-coat time of sealer

15) Paint per manufacture's specs

16) if using base-cler, then allow for last flash (usually longer than between base coats)

17) Shoot clear x(number of coats) with appropriate flash (this will give plenty to sand)

18 ) Color sand - block with anywhere from 1000 to 2000 grit

[supersuk]

so, in summary:
1) rough metal / paint to ~80 grit to allow filler adhesion (i used a DA)

2) short-strand fiberglass over welds (and seam-sealed behind)

3) sand again (100 grit)

I usually sand with 80 for filler

4) apply quality polyester filler

5) sand again (100 grit)

Depending on how well I put on the filler, I use 36grit to shape and 80grit to get the final shape and feather in.

6) follow the data sheet of primers for prep grit (wax/grease/dust removal is more important than sanding grit for primer adhesion)

7) Mask (and wet floor to keep dust down)

I usually don't care too much about dust particles in this step since it'll be covered by the high build. I don't get too much if any when spraying primer since it dries fairly fast out of that dust period. Unless you're repairing a panel, masking shouldn't be too important.

8 ) Clean with Wax and Grease remover and tack cloth

You shouldn't need to do this step unless you had to touch the car when masking.

9) Spray with high build epoxy primer

10) Block everything to 400 grit wet

Depending on the color of the basecoat, you might need to go to 600grit to prevent sand scratches from showing.

11) Repeat steps 9 and 10 until satisfied (with prep step in between)

12) spray sealer coat prior to topcoat

13) block sealer coat ASAP to remove any orange peel - follow topcoat tech sheet for grit, but good to go at least 400 (go higher if possible to minimize sand scratches showing in topcoat)

I wouldn't block the sealer coat...most sealers aren't meant to be sanded unless it has been out of the re-coat time.

14) Apply topcoat within re-coat time of sealer

15) Paint per manufacture's specs

16) if using base-cler, then allow for last flash (usually longer than between base coats)

17) Shoot clear x(number of coats) with appropriate flash (this will give plenty to sand)

Spray a maximum of 3 coats of the clear. Once dry, color sand so its flat, then respray clear again if you want.

18 ) Color sand - block with anywhere from 1000 to 2000 grit

This is how I do my painting. Others do it differently...so follow what you are comfortable with.
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68 Fastback Build: http://www.thesamba.com/vw/forum/viewtopic.php?p=5396323#5396323

[Thrasher22]

I agree, use something rougher than 100 to get the shape in. I used a lot of 40 grit (or something) to get the shape, then would do a thin layer for glazing putty to sand with lighter grits.

You can start with 100 grit, but you'll go through a LOT of sandpaper, and you'll be surprised how the cost of it adds up.

I forgot to mention, I'd recommend picking up some guide coat to use before you prime, then after you sand to prep for a top coat. It'll show you if there any deep scratches, low areas, or small pits before you paint. You just spray a light coat on, and block the area lightly with your final grit of sandpaper. The dark areas that remain are low spots
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1975 Westfalia - http://www.thesamba.com/vw/forum/viewtopic.php?t=516701

[jspbtown]

A couple of purely amatuer suggestions.

1. I go 80 grit to get the filler to shape and feather.
2. I would apply an epoxy primer then a high build polyester primer. Why? Because the polyester primer will be easier to sand than the epoxy. The straight epoxy primer will seal the metal and filler work. The poly primer is to get everything laser straight.
3. I use guidedcoat on the poly primer. If you spray it with alot of peel I would start with 220, then 400, then 600 (for solid colors). If you have real low spots shoot more poly primer, guidecoat and sand.
4. I would then use your epoxy primer thinned down as a sealer when all the guidecoat is gone. Don't sand the sealer
5. Base goes on "wet" sealer (after appropriate flash).
6. Double your flash times for the clear. I have found that if you don't wait long enough you can get solvent pop or as the clear gets heavier (needed for color sanding rookie paint jobs) then you get large sags in the clear. Most clear has 18 hour re-coat windows so going 30 minutes (or 40 minutes) between clear coats is just fine. Its just a pain to sit and wait.

Just a few suggestions.

[supersuk]

For the guide coat, I'd suggest the 3M drycoat. Its simply the best guide coat there is. Sure its expensive, but it is much cheaper than the amount of time spent sanding. That $40 drycoat will also go a very long way.
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68 Fastback Build: http://www.thesamba.com/vw/forum/viewtopic.php?p=5396323#5396323

[mango-smoothie]

just to be clear - the sealer is not to be sanded? why is that? what if i get a run?

The primer i am using is crazy thick (1.5-2.5mm per coat). as a sealer (4:1:1.5), i plan on still using the 1.8mm gun

(i'm at the blocked to 280 stage)

[Thrasher22]

2.5mm thick? Are you spraying undercoating? That sounds wayyyyy too thick.

You can definitely sand clear, people do all the time when color sanding to get runs/ orange peel/mistakes out.
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1975 Westfalia - http://www.thesamba.com/vw/forum/viewtopic.php?t=516701

[jspbtown]

Yes you can sand sealer if you get a run. Sand the run out, scuff and re-seal.

With paint or primer you need to think of chemical bonds versus physical bonds.

When you spray your high build you have a physical bond between the roughness of the surface and the hi build. The hi build cures thoroughly before you can sand it so a chemical bond with a sealer (or paint) is impossible.

The sanding allows not only for a smooth surface on the hi build but also the teeth needed for the physical bond of the sealer. The paint is applied to the sealer before it is cured and results in a chemical bond between the sealer and the paint.

The same is true for the clear over the paint. Clear is sprayed before the paint is cured so you get a chemical bond.