Calling the Usual Suspects

I'm attempting my first show-type finish job--doing some clamshells for a 460. Not a big job and one that I can put some time in to perfect some techniques. A fellow club member has a JD 435 with a finish job that literally takes your breathe away: its main characteristic is its rich and ultra smooth paint job. Hey! I can do that, too.

I've finished painted a lot of iron before (forklifts, backhoes, tons and tons of structural steel) but never really got good at laying down a nice finish coat and quite frankly, these weren't really show pieces either.

Prepped the fenders by sanding and blasting the stubborn areas, cleaned with phosphoric acid wash followed by two coats of etching primer (good stuff--DuPont), standard primer, sanding/filling, more primer etc until satisfied with the surface texture.

Time for topcoat: DuPont Centari (code# matched with paint Dad used on the 460 paint job in 1998) with hardener yada, yada, yada. Laid down thin first coat (a 'tack' coat) followed by a good cover coat, let dry for a couple of hours, then hit her again. Ah yes, good old orange-peel mixed in with a texture akin to the rubbery material my Ranger dashboard has. Don't think I can attribute the texture to paint being too thick. I have spilled more paint than a lot of folks have sprayed and have learned that generally paint is usually applied with a too-thick mixture.

Now... I know you have to color sand, but it seems to me that the guys that know what they are doing probably don't have to sand as much as what appears I need to do to flatten things back out. They don't have forever to get things right.

Just got done color sanding. Did the bulk work with a DA and 180 discs then wet-sanded with 320 then with 1000 grit. Surface is now smooth and yes, there is still red paint on the fenders.

I admit my spray gun is what you might call from the "cost-conscious" line of tools, but it should get at least closer to a flat job than what I've been getting.

Is this a fact of life, and how many coats to lay down before final rub out? I'm believing it's a fact of life: we've done work in the local Honda Car Plant paint shops and even the factory jobs have a slight orange peel look.

Two things outlined by you guys are evident. For starters, I'm waiting too long between coats--fearful of causing runs. Secondly, I'll flat guarantee you I'm spraying at too low of pressure if what you recommend is in the 60 PSI range. I sprayed at a regulator setting (at the compressor) of 50 PSI thinking that at the gun (at the end of 75' of hose)pressure would be about 45 PSI. I always believed that high pressures woofed up the paint at the surface creating small waves allowing the higher velocity air to 'freeze' these waves in place--sort of like the wind creating waves on a lake. Sometimes I think too much.

I'm using Mix #2 as decribed by Rod, and I did notice significant orange peel prior to the last coat.

Well..as decribed in my post, I'm now ready for round two. This will be done per you recommendations.

I get quite a kick out of all of you guys and your experience. It's a snap to copy and paste your responses to painting questions into a Word file. I'm building quite a library.

Centari is field-mixable in three different ways:

1) conventional acrylic enamel (AE) w/o hardener (AE + reducer - also called 1K pak)

2) AE w/hardener (AE + hardener + reducer)

3) Urethane modified AE (AE + urethane activator + ultra performance pak reducer). This is referred to as "Centari Ultra" or "Centari with Ultra Performance Pak".

You are apparently using either 2 or 3. I haven't used Centari in recent years except for two years ago when painting one of my trucks. My prior experience with it had been with mixes 1 and 2 above - pretty conventional. When I did my truck, I used version 3. Big difference in technique! Centari Ultra is applied in three full wet coats (no discernable "tack" coat) in cross coat fashion (latter coat 90 deg to previous coat rather than parallel). And no flash time between coats! As soon as you complete the first coat, go immediately to the next. This stuff is very hard to run. You almost have to work at it to do that. I was surprised as it was quite different to what I had been used to before. If you wait the conventional flash time between coats, it may retard the final flow out and contribute to more orange peel.

If you were using the #3 mix, you might want to try the above on a vertical test piece to get the idea. I also think that waiting the "couple of hours" prior to the final coat could also have been part of the problem. Usually you wouldn't do that, as far as I know. Did you notice any significant orange peel prior to that last coat?

I am not into "show quality" or high end stuff so I simply don't bother with any color sanding and buffing. It's not worth the effort for me. You really should be able to get it smooth with little if any orange peel without all that extra work. You also want to pay attention to proper atomization. Make sure you use the correct air pressure AT THE GUN INLET. Tee in a pressure gauge there to verify it with the trigger pulled. And make sure you use the correct reducers or paks (there are at least four of each) for the temperature at the time of spraying.

My thoughts anyway.

Rod