Fixing Sand Through

While level sanding the water-based lacquer on one of my guitar builds, I accidentally sanded through to the wood on one of the sharp edges. Here is how I fixed it:

Even with a light touch and 800 grit sand paper, I still managed to sand through to the wood on this sharp edge.

No problem. I just wiped on some of the paint I had left over from spraying the back. It took about three coats to cover the damage.

Next, I used a q-tip to apply some clear water-based lacquer. Four thick coats were applied about thirty minutes apart.

After the last coat of lacquer had dried, I lightly sanded the area with 800 grit to blend. Now I can proceed with wet sanding the whole body. Hopefully, I won't have to deal with any additional sand through before I buff. If I do, I'll repeat the process.

This Little Light Of Mine, I'm Gonna Let It Shine...

No, I am not going to get all religious on ya. What my headline is referring to is how I judge a buffed out lacquer finish.

After the lacquer has cured for a week, I wet sand the body with P1000 grit paper to level the surface. Then, I quickly move through P1500 and P2000.

One might think that at P2000 grit, the surface would be ready to buff. It isn't unless you start with a very course buffing compound, which I don't like to use due to its aggressiveness. Before I can buff, I like to go over the surface of my guitars with Micro Mesh sandpaper. I start with 3200 grit and work my way through all of the available grits to 12000. I use the same technique I used with the wet/dry paper except I spend less time with each grit.

After finishing with the 12000 grit, I polish the surface on a buffing machine, starting with Menzerna Pre-Polish. Then, I move to another wheel loaded with Menzerna Very Fine polish. Check out the results:

It took me a couple of years to perfect my technique, but the results were with the effort.

I know I am finished buffing when I can clearly see the reflection of my lamp without any scratches.

Putting The Shine On

Yesterday, I wet sanded one of my Envirocaster guitars and put it to the buffing wheel. For subscribers to my newsletter, I will detail how I achieve a mirror like shine in the next issue.

Build Updates: Both Envirocasters Get Their Final Coats of Finish

I hate wet sanding, however, it is a necessary evil if you want a glass-smooth finish. For these two guitars, I'm trying a slightly different approach that will hopefully dramatically reduce the time I spend wet sanding.

What I did was spray 7 coats of water-based lacquer. After they dried over night, I dry sanded with 320 grit. Then, I sprayed another 7 coats. This morning, I dry sanded with 400 grit and began spraying what I anticipate will be a total of 5 light coats. The first is very smooth. If I can keep it that way with each coat, I hope to be able to wet sand with only 2,000 grit. We'll see, but I'm optimistic.

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.

Top Coating A Guitar With Target Coatings Emtech 6000

For my current electric guitar build, I've decided to try out Target's Emtech EM6000 water based acrylic lacquer as a clear top coat. In the past I've used Hydrocoat's Resithane Plus with great results, but I wanted to try EM6000 because of it's burn-in capability, which the Resithane Plus lacks. What this means, is I won't have to sand between coats. That feature alone will mean a lot of time saved.

Instead of spraying on the EM6000 with an HVLP sprayer as I normally would have done, I decided to brush it on since other luthiers have had success with this approach. Water based lacquer in my opinion is harder to spray than nitrocellulose lacquer because it take longer to tack up. For that reason, WB lacquer has a greater tendency to run or sag before it sets up. This can be a real problem with all of the curves and angles found on a guitar.

Brushing WB lacquer, however, is not full proof. Regardless of the type of brush you use or whether the lacquer is thinned with either water or retarder, you can expect a significant amount of air bubbles in each coat you lay down. Fortunately, I chanced upon a technique which eliminated the air bubbles completely. I'll explain in a moment.

The first step in applying the top coat is to make sure the surface is ready. That means it has to be smooth with all of the grain and pours filled in. I started the prep work by sanding the guitar with 220 grit paper to get the surfaces nice and smooth. Because the body of the guitar is made from Honduran Mahogany, which is an open pour wood, I had to fill the grain. To do this, I wiped on a liberal coat of boiled linseed oil and sprinkled on some 4f pumice. The pumice turns clear on contact with the BLO and as I worked it into the wood, it generated wood dust to form a paste, which fills the pours and grain. I used my bare fingers to rub the paste with a circular motion into the wood. After the entire surface had been rubbed with the BLO/pumice/wood dust mixture, I let it dry over night. The next day, I wiped off the excess grit with a tack rag. Then I let the body dry for 4 days. The neck on the other hand, is made out of Maple, which doesn't require grain filling.

After the 4 day drying period, I was ready to start brushing on the WB lacquer. The process is simple. I dipped my soft, 2" wide brush into the can and spread it over the body and neck as if I were painting it. Since WB lacquer is rather runny, I had to be conscious of runs, especially down the sides. This was no problem as I caught them when they formed and brushed them back into the rest of the wet coat.

At this point, I was dismayed by the formation of thousands of tiny air bubbles. In many spots, the lacquer actually turned foamy. To rectify the situation, I immediately grabbed a small 6" square piece of clean, 100% cotton cloth, moistened it with water and formed it into a ball. With the first coat still wet, I rubbed the cloth back an forth in a pendulum motion from one end of the wood to the other sort of like a French Polishing technique. This effectively removed the air bubbles and spread the coat evenly over the surface. The only downside to this technique is that it leaves subtle brush marks in the surface. However, since I knew I would have to level sand the surface before buffing, I wasn't concerned.

Each coat went on about 30 minutes apart and after 16 coats, I decided that was enough. The instruction from Target Coatings recommends letting the finish cure for 100 hours before polishing. However, with so many coats, I decided to let the body and neck cure for a week.

Level sanding consisted of dry sanding the body with 800 grit silicone carbide paper. Dry sanding at this early stage of leveling allows you to better see what's happening on the surface. The WB lacquer turned to white powder as I dry sanded it and when after wiping the surface with a tack rag, I could easily see the high and low spots. The goal was to sand the entire surface to a uniformly matte appearance. It happened very quickly and I only had to apply very light pressure.

Once I was satisfied the entire surface was level, I began wet sanding very lightly with 1,500 grit paper dipped in a mixture of water with a few drops of Murphy's oil soap for lubrication. Then I switched to 2,000 grit to finish. At this point, the surface had become quite reflective. However, it wasn't shiny enough. The buffer would take care of that.

I buffed with two 12" soft flannel wheels. On the first, I used Menzerna medium compound to remove any remaining fine scratches left by the level sanding. Very light pressure is the key as too much will overheat to lacquer and cause it to blister. On the other wheel, I used extra fine Menzerna compound, which gave the body the much desired wet look.

I'll shoot some photos when time permits and post them here for you to see the results. Stay tuned!