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Monday, July 23, 2018

Raptor Liner with HVLP Gun - Triumph Spitfire Restoration


I got to the garage nice and early on Sunday and got right to work. First up was to double-check my scuffing job on the epoxy. A few spots needed attention, but otherwise it was good. I mixed up some epoxy primer (normal 1:1 ratio primer:activator) and, while that induced, I got those spots done.
I cleaned it all up with wax and grease remover and then, using a 1" chip brush, I epoxied the spots in the rear wheel arches and a large area under the dash that I missed. I had intended to spray that spot under the dash, but the epoxy went on so well in the wheel arches with the brush, that I figure that was easier and would save cleaning time.

After the first coat, I had to wait 30 minutes before applying the next. During that time, I modified my  Harbor Freight "Purple Gun".  It was a whole $10 with a coupon and, though it's  a piece of junk, it fit my purposes exactly.

If you've ever seen a typical painted truck bed liner, you know that it's pretty roughly textured. I wanted something smoother than this but to get it, I would have to use an HVLP spray gun instead of the bedliner gun that comes with the Raptor Liner kit.  Unfortunately, the purple gun comes with a 1.4mm tip and HF doesn't seem to sell any other sized tips separately, so I had to modify it myself to meet the 1.6mm to 2.0mm tip size that Raptor Liner specifies. I used a 5/64" drill bit to make the tip just shy of 2.0mm.

In the drill press to try to get it as straight as possible.

Post drilling. Rather anti-climactic, but it worked!

When I got that done, it was time for the second coat of epoxy  under the wheel arches and dash and  then I waited another 30 minutes.

Under the dash area fixed. Trust me that there was a large missed area here. You may notice the brush lines.

After the 30 minutes was up, it was time to spray a sealing coat of epoxy over the underneath in preparation for the Raptor Liner. Since I was outside of my 7-day topcoat window for the epoxy, I needed to take additional measures to ensure proper adhesion. In this case, SPI directs scuffing it with 180-grit sandpaper and a maroon Scotchbrite pad. Then, spray a reduced coat of epoxy primer, wait 2 hours, and apply the topcoat.

With the underneath scuffed, I cut the remaining  epoxy primer from my touchup (I mixed enough for the underneath as well) by about 25% with urethane reducer, then sprayed a single wet coat over the entire underneath.

Hurry up and wait...

Then, the wait was on. Unfortunately, I didn't plan that far ahead so I didn't have much to do for 2 hours. I tried to clean up a bit, ate lunch, and generally tried to pass the time.  With about 30 minutes left in the wait time, I started mixing the Raptor Liner.

The purple gun has a 20oz. cup. Since I needed to mix the Raptor Liner, its activator, 10% tint (the SPI medium red basecoat), and 10% urethane reducer to get a smoother texture and make it easier to spray, I decided to mix it by weight.

Raptor Liner provides a convenient table with various weights on it. I bought a digital scale (didn't want to wreck the one from home) for about $10 from Amazon.   To make sure I could get it in the purple gun's cup, I mixed 500ml of Raptor Liner (~420g of Raptor Liner and ~120g of activator for a ~3:1 mix), then 54g of tint and about 54g of reducer.

The SPI Medium Red basecoat; my tint.

I combined it all in a quart cup and mixed it for a while, about 5 minutes. Even reduced, the stuff is pretty thick and I wanted to make sure I got it well mixed.

Quick safety tip: As with all automotive paints, at least in my experience, you need to be careful and wear the appropriate safety gear. The Raptor Liner has something called isocyanates in it. This is nasty stuff. If you remember that Union Carbide chemical release in India in the 1980's that killed several thousand people...yeah, this is that stuff. I wore a full-body paint suit, with hood and booties, an organic vapor mask, and safety glasses. Fortunately, the Raptor Liner is so thick that it doesn't go airborne anywhere near like the epoxy primer does, but that's no reason to take any chances. Wear your safety gear!!!

With the mixing done, I transferred it to the paint cup (it just fit) and went into the booth. I did a quick test pattern and it looked good enough, so I started applying.  The stuff went on pretty slowly and I had to change my method of application from shooting the epoxy. I also got within just a few inches of the surface to get good coverage.  The first mix got the boot floor and rear wheel arches and cross-member right up to the floor boards. I mixed another 500g to finish it out. This stuff doesn't require an induction time so you can shoot it as soon as it's mixed, which is convenient.

From the front.

From the rear.

I even remembered the spring cover!

Once all of the initial spraying was done, I went back in with a flashlight and got any spots that I missed; there were lots. My "booth" isn't very well lit so I needed the bright light to help.
All in all, I was very happy with this stuff. I was surprised at how strong the color was given the amount that I used (didn't seem like a lot). And the stuff goes on brainlessly easy. It's so thick that it's nearly impossible to get runs and, since it's a textured product, it's all about epic orange peel, so you don't really care about how "clean" it looks.

Unfortunately, with all of the wait times, my garage time came to an end after the first coat. I contacted UPol today about applying a second coat, which they highly recommend. Normally, the wait between coats is 60 minutes. UPol told me that the recoat window is from 60 minutes to 5 hours. If you exceed 5 hours, wait 24 hours, then lightly scuff it up and re-apply. They said you can do this a week, a month or even years later. Just make sure it's clean, scuff it, clean it again, and shoot. The scuffing may be a bit painful with the texture, but that's what I intend to do on the next visit.

Once the second coat is on, I have to wait from 5-7 days before applying any "weight" to the Raptor Liner. The next step for me is to remove the wings to get them out of the way and get the body back on the sawhorses to start doing body work. I'm hesitant to do that inside of that 5-7 day window in case the weight of the body resting on the sawhorses messes the Raptor Liner up, so we'll see. I can always go back to the doors while I'm waiting!

That's motivating!

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