Sunday, May 25, 2008

Sanding Sealer and Color

Its been a good week. I progressed through the sanding sealer stage and got the color coat on. The sanding sealer is a high solids lacquer that builds quickly and sands easily. From what I've learned the application of sealer provides two advantages. First, the sealer separates the wood from the color coat, helping to ensuring an even application of color. Also, by block sanding the sealer with fine grit paper, pits and other imperfections are revealed as shiny areas in what should otherwise be a perfectly flat surface. This allows the problems to be found and corrected, further improving the chances and ease of obtaining a glass like finish later on.

I sprayed two fairly heavy coats of Deft sanding sealer and then sanded with 320 grit. There were a few pits over some grain pores, but they were extremely small and I could see that they did have grain filler in them. So I sprayed another two heavy coats and sanded with 400 grit -- luckily I was able to get the body flat without further corrections.

On the Friday night before Memorial Day weekend I built a plastic tent in the garage -- i.e., my "spray booth". I thought it was perfect timing since the final clear coats should be applied over a consecutive three day period. But the lacquer must also be applied when the humidity is low to prevent "blushing", a white film caused by the presence of moisture in lacquer. While I was constructing my spray booth it started raining. I woke up Saturday morning to more rain and 75% humidity. Grrrr.

The weather finally decided to cooperate in the afternoon and I was able to get the color and a coat of clear on. I was a bit nervous about this step, but it turned out not to be a problem. The color was applied using 3/4 of a can of the ReRanch Fender Translucent Blue. I was afraid of getting uneven color -- so I just took it slow and stopped when I thought the color was right. Its actually somewhat darker in real life than it appears in these photos.

While spraying the clear lacquer coats on Sunday I noticed a tiny ding on the front of the body between the bridge route and the arm rest. I must have dinged it at some point after finishing the sanding sealer. To correct this problem I "drop filled" a small amount of regular lacquer into the ding with a small fine-tipped paint brush. Hopefully this will solve the problem, if not I may have to repeat the drop fill procedure.

Friday, May 9, 2008

Grain Filling - Part II

The body is back in reasonable shape by sanding with 100 and up to 220 grit sandpaper. At one point during the process I wiped it down with naphtha and found more scratch marks so I continued sanding. The rear of the body has quite a bit of filler in the pores from my previous attempt. It looks good but the sanding has opened new pores and it needs to be filled again.

For the washcoat I followed Dan Erlewine's advice from my copy of "The Guitar Player Repair Guide" and used one part lacquer to three parts thinner for the washcoat, which I brushed on -- twice. The Deft gloss brushing lacquer and Klean-Strip lacquer thinner don't mix well -- I had to shake the solution every couple of minutes while applying it since it separated out pretty fast.

Thats the thinner on the top. Most of the solids in the lacquer settle to the bottom and form the yellow layer.

I mixed up more filler. Shown below is the Minwax ebony stain, the Bartley's natural paste wood filler (grain filler). The cup in the foreground contains a spoonful of the filler mixed with about 20 drops of the stain.

Here's the body before grain filling...

Shown below is the progress after two coats of the grain filler. The horizontal streaks are from scraping the grain filler off of the surface after it glazes over. Some filler is left on the surface and will get sanded off later.

This is the body after sanding...

And some pics of the body after getting a coat of lacquer to lock in the grain filler...

I'll be applying a translucent blue color coat later in the process...


Monday, May 5, 2008

Grain Filling - Part I

This project is going to take longer than I thought. I made some progress with grain filling but sanded most of it out to correct two problems - blotching on the sides of the body and tool marks revealed by the stain.

The blotching is probably due to a poor washcoat which consisted of only a couple of light misting passes of Deft aerosol lacquer. I've since learned that the best washcoat is a mixture of 1 part lacquer to 3 parts thinner.

The tool marks were not visible until the grain filler was applied. And even though the body looked perfectly smooth before I started, it quickly became obvious that I should have done a thorough sanding first.

The good new is that these problems can be corrected by sanding and a better washcoat.

Here's the rear of the body with the grain filler applied, but before sanding. Note the contrast with the tremolo route which is not grain filled.

This image shows the blotching that occurred on the sides of the body. After sanding this out, I hope to solve the problem with a better washcoat.

Here is the rear contour tummy tuck. Click on the image to view at full resolution and look closely -- you should be able to see circular tool marks revealed by the filler. These weren't visible before the grain filler was applied. I'll be sanding these out before re-applying the filler.