Friday, September 3, 2010

Mix and spray Etch Primer

Time to paint the Porsche 944. Today I'm applying the the first of all the layers of "paint": Sherwin Williams Lead and Chromate Hazard Free Etch Primer (FP301). The etch primer prevents the aluminum from corroding, and maximizes adherence for subsequent layers. I keep reading that it chemically bonds with the metal to form a stronger base, though it seems to me it just has some chemical components that neutralize oxidized metal; Nothing in it to make it more "sticky", but I digress.

It is mixed 1:1 with a Reducer (FP302, $32 per quart). I originally bought two quarts of the etch primer, and a gallon of reducer (which only comes in a gallon size!?, $55). It turns out that I only needed one quart, so my costs for the etch primer were $87 total. My favorite part is that it is made by a company called ACME, which brings back good memories of Wile E Coyote. I hope this stuff works better than his ACME products!

The primer mixed up really easy. (Don't forget to shake the bejezzus out of it first). It is a really pleasing shade of olive green. I used some cheap mixing cups I picked up at Home Depot, though after further review the ones at the paint store are just as cheap and have more accurate lines than the H.Depot ones. Here is Jesse mixing up the etch primer:


While he was mixing up the paint, I went over the whole car twice with Kleen-Strip Prep-All Wax and Grease Remover (1 gallon, $18), rubbing it on with one heavily-doused shop-style paper towels (1 roll, $2), and then wiping off the excess and residue with a second dry shop towel. I did the whole car once, switching towels only as they got really clogged with dust and dirt. Then I did the car a second time using a new set of towels on each panel. (The cost of a few extra towels is minimal compared to having to redo all the upcoming work + materials.)

I'm pretty excited to finally start spraying. Since I'm a novice, and my buddy (who is a great painter) is a gimp, and used to painting cabinets; the next step was a little daunting. You don't think about it until you have the spray gun ready to go, but the action and order of spraying the car demands some forethought. Special thanks to Kevin Tetz's Paintucation videos that took the time to give the best plan for painting the car. First off, here are some "before" pictures. I am totally sick of the look of scrubbed mottled aluminum, and ready for some uniform color:

Kevin Tetz makes a good point. Before spraying your paint, take your gun with hose attached and pretend to paint the whole car. It will give you a good idea of where you might need some extra thought of order of progress, and how to hold the gun in trouble spots (like the bottom edges of the rocker panels.) It also helps you notice when your hose might hit the car so you can work out a system from keeping the hose away from wet paint. You could even do it with air, but no paint, and see if any of your masking gives way to air pressure.

Per Tetz, start at the roof-line of the car above the doors. you paint from front to back starting above the door, and painting in long even lines. Each row overlaps 50-75% and is that much closer to the middle of the roof panel, each stroke starting from the windshield and going back to the hatch area. Once your strokes reach the middle, go to the other side of the car, and starting where you left off in the middle, continue the strokes until you've finished the top of the car. I then painted down the side of the windshield pillar on each side (that diagonal bar that also has the edge of the front door), I'd leave the rear pillar for later. Here is me starting to spray:

Next up, spray from the outside edge of the hood over the front fender (with long strokes from the windshield to the front nose) working your way towards the middle of the car on each stroke. Once you get to the middle, switch to the other side of the hood, and work from the middle where you left off, until you get to the front fender. Here you can see I've just gotten to the middle of the hood and am switching sides:

Once the hood is down and your strokes have reached the fender, you can paint one long long stroke from the front of the hood, along the fender, along the top of the window all the way to the back of the hatch at the corner of the car. Stay on the same horizontal line, which means you will have some unpainted area around the rear pillar. once you finish this long stroke, then keep making horizontal passes above that one on the rear quarter of the car and along the edge of the hatch until you've got everything above your first long stroke done, including the whole rear pillar up to the roof-line.

Then, starting at the rear corner, lay another long horizontal pass overlapping with your first long pass, along the length of the car. Continue these horizontal passes with 50-75% overlap until you've done the whole side of the car from hood to rear corner. Don't do the wheel well edges and bottom of the rocker panels until you've finished the whole side of the car. A little over-spray here is OK, and they should be mostly painted during the long passes.

Once you finish the first side, go to the other side of the car, and pick up where you started the hood earlier, and paint the second side of the car as you did the first. Once the side is done, move to the back of the car and paint from top to bottom, making sure to avoid over-spraying in the license plated holder area, and the rear taillight areas which have so many angles and inverted spots. I got a few drips around here the first time through. The etch primer was nearly opaque: there were only a few spots I could still make out the bodywork or bondo edges underneath. Here is the car after one medium-heavy coat:

I let the etch primer flash dry per the instructions using a kitchen timer for accuracy, and spent some time on my hands and knees to make sure there wasn't a single missed spot. I then re-sprayed the whole car again with a light-medium coat. After this second coat, everything was really even and totally smooth with only the slightest orange peel (bumpy paint texture.) I had about a cup of paint left, and after the second coat flashed, I sprayed spots that I thought might get more wear during sanding, like the hard edges on the hood and fender corners. I totally forgot that I had several pieces that I had on saw horses to paint because I was so excited. Don't forget to etch primer your gas cap, front and rear bumper, rear view mirrors, and rain gutter trim edges. I forgot about these parts and kept spraying until the etch primer was all gone. Oops.

I can't tell you how great this step felt. All those extra hours sanding the bondo just a little bit more were worth it. The uniform color makes such a huge difference, and all the family came out to ooh and aah at my now olive green Army-style Porsche 944. I had half a mind to paint some camp spots on and call it good.

Once the etch primer was hand-slick* I threw a brand new 1-mil plastic sheet over it to keep of dust and minimize how much tack clothing I'll have to do before primer. This is a good idea if you spray in the next 24 hours. My etch primer calls to be scuff sanded after 24 hours, which it ended up being, so the drop cloth was a waste. Here you can see the drop cloth over the car, and I turned off the halogen lights which give everything a sickly yellow glow. This green is the actual color of the etch primer.

Notice that we didn't set up the booth for this step, since it will all get sanded down. I was surprised how many bugs got their legs stuck in the paint. Plus there was tons of dust that landed in the paint and really looked bad. I was very surprised, even though my vent fans both had filters on them.

The etch primer is pretty thin, so I sprayed it using a 1.3 tip on the spray gun. (More on the spray gun in the next post)

*Hand slick - My paint jobber, Beth, was kind enough to tell me what this means. When the paint is looking like it has dried a bit, touch the back of your finger, gently, to paint that is on your masking paper, not the car. If the paint sticks to your hand, it is still wet. if you can touch the paint with the back of your hand and it is not sticky, then it is hand slick. But either way, if you check on the paper that has been over-sprayed (like on the edge of the windshield) then you won't mess up your paint if it is still wet. Thanks Beth!)

Total time spent: 2 hours
Total money spent: $107 ($87 etch primer, $20 cleaner and towels)

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