Saturday, February 19, 2011

Finishing With Water-Based Lacquer

There are a couple of notable differences between water-based and nitrocellulose lacquer as far as how they are sprayed and how they dries. Nitro starts to tack up the instant it leaves the spray gun or can and it's usually dry to the touch within 10 to 15 minutes. This characteristic makes it easier to avoid runs, but often results in orange peel if the sprayer is held too far back from the surface. Of course, if you spray too close, runs can and will happen. You have to find a happy medium in terms of far away and how fast you sweep the surface as you spray.

Water-based lacquer, on the other hand, seems to stay wet no matter how far back from the surface you spray. In fact, each coat takes about 30 minutes to an hour to dry. For that reason one needs to be aware of airborne particulates like dust. You don't need a spray booth (although if you have access to one, certainly use it), but it helps to move the guitar into an enclosed space like a closet right after you spray where it can hang to dry.

Like nitro, water-based lacquer also exhibits orange peel. My experience, and what others have told me, is that this is par for the course with WB lacquer. The difference is that WB lacquer's texture is more like an orange peel than nitro. Nitro feels more like 80 grit sandpaper. The good news is that you can sand out the orange peel from WB lacquer very easily. In fact, I usually start with 800 grit rather than 400-600 like I do with nitro. This means wet sanding takes far less time with WB lacquer.

A close-up of the orange peel texture common with water-based lacquer.

The biggest difference (and the reason why I love WB lacquer) is the curing time. Nitro take about 3 weeks to cure before you can level sand, however, WB lacquer takes only about a week. It cures even faster in dry climates like I live in.

Buffing out the finish to a mirror-like shine is also where WB and nitro differ. With nitro, I really have to push the surface into the buffing wheel to remove the scratches left by the final 2,000 grit sanding whereas with WB, I only have to lightly touch the surface to the wheel.

One might assume that since WB lacquer is so easy to sand and buff that it must be less durable than nitro. However, according to the manufacturer I use (Target Coatings), WB lacquer is much harder than nitro. I have a couple of guitars hanging on my wall right now that bear this out.

When you consider other differences like how flammable and toxic nitro is (it's illegal in some places to use), water-based lacquer and its lack of fumes and easy clean-up make it a no brainer IMO. I still dream of the day when a lacquer will become available that dries to a mirror-like finish right out of the gun without any wet sanding or buffing, but until the chemists can make it a reality, I'll have to keep the wet/dry sandpaper and buffing compound at the ready.

2 comments:

  1. Hi Chris,
    could you please comment more on how you do the sanding to avoid orange peel? I have used WB lacquer and finished exactly with the picture you have shown. Then I tried to use 1000 grit paper (without water added) to sand using electric sander. And the result is horrible. As the lacquer layer was not the same thickness, on some places I basically sanded through, while on other places the same sanding time did not even remove the peel.

    any hint appreciated

    david

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    1. Anything you finish with a gloss top coat should never be touched with a machine until you buff. If you're happy with the top coat, then wet sand by hand using a medium 3M sanding pad, use the same method working your way up to 2000 grit, then buff the whole thing for a mirror like shine!

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