July 11, 2009

Priming Fuselage Parts - 6.5 hrs.

At long last, I'm finally shooting some paint! Today was my first experience with new paint guns, new paints, and entering the big learning curve. I mixed up some of my new primer, stirred it frequently for the 30 minutes required, loaded it in the gun, and started priming.

I first started priming the forward ends of the longerons. The aft ends are already primed with my standard SEM primer that I've used throughout the project. But the forward ends are visible inside the cabin so I will spray them with the JetFlex next. I clamped them to my little portable workbench and they hung here in just the right position to easily spray them. When this was dry enough, I flipped them over and re-clamped them to shoot the other sides.

Here's my big table full of parts, all primed. It's a beautiful summer day, temperature in the mid-80's, no wind. Perfect for this work. When it was dry, I flipped them all over and shot the other side. Next, I tried shooting some JetFlex topcoat on a few of the parts. It didn't work out too good. I don't have any pictures to show yet. Even though the primer looked totally dry, the JetFlex would bead up in some spots. I realized that it wasn't totally dry, even if it looked like it was. I will have to wait overnight to make sure the primer is totally dry, and try again tomorrow.

So how are the paint guns working out? How's the experience so far? Well, honestly, I'm getting mixed results. I'm very impressed with the Harbor Freight HVLP gun so far. The primer was easy to spray and not get runs or sags or orange peel, as you can see above. It's great! I was worried when I first opened the can because the stuff is so thick. The product data sheet mentions a reducer that can be used to thin it down, but they didn't recommend it to me so I didn't get any. I was worried until I mixed in the adducter. It didn't make it even thicker, as I feared it would. It thinned it down to the perfect consistency to spray. The one problem I have is that I don't seem to have enough air flow. I pull the trigger and shoot for a moment and it's fine, but then it diminishes down to almost nothing. I run out of air and have to wait for a few moments for pressure to build back up in my air line. It's frustrating, and it slows things down. I don't know where the bottleneck is in my system. I'm going to have to troubleshoot to find out. In spite of that, I'm pleased with the priming results.

How about the JetFlex? Well, it's a completely different animal, of course. It is thicker, like a latex house paint, but the data sheet says you can shoot it at this consistency anyway. So I tried it. Different paint gun, too. I used my Devilbiss gun for the JetFlex. I'm realizing that there are so many variables, it will take a while to sort through all of them to find the best combination for me. My biggest frustrations were: 1) the primer wasn't totally dry; 2) once again, I didn't seem to have enough air flow, and 3) the results were mixed on the finished appearance. I'm not sure if I should reduce, or thin the paint with distilled water or if I'm just not shooting it correctly. I'll be trying again tomorrow.

I'll say this much. I am SO GLAD I decided to paint these parts now before riveting it all together. And I'm glad I went with a water-based topcoat. Several times, I was able to take a part I messed up and just hose it all off with water so I could start over. You can't do that with a riveted-together fuselage! I can't imagine going through this learning curve with a finished fuse.

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