Advice on water-based spray finish

[Ron Zentz]

I'm an experienced woodworker turned luthier (working on #2). My finish experience with nitrocellulose lacquer is limited to the spray cans, with OK results. I don't have a spray booth but sprayed outdoors. I'm thinking of spraying the water-based lacquer that StewMac sells: Target Emtech 7000HBL. Is anyone using the product? Other recommendations? I'd like to go for a gloss finish but without the nitro solvent concerns. I'm in a heated garage shTsop in Indiana. No spraying outside for a few months!

[Bob Gramann]

I spray Target EM6000 that I purchase directly from Target Coatings. I use an Asturo ECO/SX gun with a 1.3 mm tip. I have tried the em7000 and had trouble getting the same results that I got with the em6000. It may be that I didn't stick with it long enough to get past the learning curve, but I was getting good results with the EM6000 so I went back to it.

It helps to raise the grain of the wood and sand it back before finishing. I use shellac as a base coat. Any pore filling is done between shellac coats.

I spray into a box connected to a serpentine duct to a fan with a washable filter to catch the overspray. The fan exhausts through a window (another window is opened to provide make up air). The long duct allows the overspray to dry before it hits the filter--that way the filter can be cleaned instead of discarded.

I spray 4 coats a day for 3 days for a total of 12 coats. At the start of each day, I level the previous day's coat with 320 grit paper. Each coat takes 20 to 30 minutes to dry enough to be handled and recoated. Results are better and easier if the gun is good enough and set well enough to really atomize the coating. Before I upgraded to this gun, it took me quite a while to level the orange peel that I got with the old cheap gun.

I let the finish cure for 7 or more days before I do the final leveling with 800 paper and then polish it out. I'm real happy with the results.

[Gordon Bellerose]

Yep. I'm with Bob.
I also use Target EM-6000 clear lacquer. Pretty much the same method also. I have heard that the EM-7000 dries with a tinge of blue. This is not real bad depending on the color of your guitar, but could foul up a natural or woodgrain color.

My last 4 builds have been done with EM-6000.

One was flamed Maple, and I stained black and sanded back lightly, to show the flames. Then I stained red, and then shot clear coats.
There are pics in another thread called "My latest Build."

Another was Ash, walnut, and cypress, and I sealed with shellac, filled with epoxy, and then shot amber stain mixed with clear, and then clear coats.
The next was Mahogany, using the same method except for stain.

After that was a burst, done on Ash again. This time I stained the center color first. Then I sealed with shellac, sanded lightly and shot two coats of sanding sealer. Sanded back again and shot two coats of clear. After two coats I shot the burst edges, and then finished up with clear coats.

Again like Bob, I was using a cheap HVLP gun, and was not happy with the results, but after buying a good, heated gun, with a 1.4 tip things went a lot better.

[Ron Zentz]

Gordon and Bob...thanks for the great responses and advice. My plan is to buy a HVLP system (been thinking about that for a long time) and use a set up like Bob described. I can spray a test case or two first and see if the gun supplied will work for me. I am working on a dreadnaught of indian rosewood, engelmann spruce and a mahogany neck. Curly maple binding and some abalone purfling and D45 fretboard inlays. My nephew is getting excited! I think I will fill pores with StewMac's water-based filler. I used epoxy last time and it went OK but I just don't like working with it. Do you guys ever use the em6000 sanding sealer (assuming there is one like for the 7000). If you have any suggestions for a HVLP system or a gun make and model let me know.

[Bob Gramann]

Much of the research I've done suggests that a compressor with an HVLP conversion gun is more versatile than a turbine system. The gun I use is stated above. if I could determine that there was a system that would spray without orange peel and less overspray than what I have, I would probably buy it. Cutting the overspray increases the orange peel with my gun.

I don't use sanding sealer but rather shellac (flakes mixed with Everclear) as a base coat.

[Gordon Bellerose]

I do not have any experience with a turbine system, but in all my reading the compressor powered systems come out on top.

Bob. The heated gun I bought works very nicely. I did have to upgrade my compressor though, as it is a bit of an air hog, requiring 5.8 CFM at 90 PSI. It was costly though. I got it on a really good sale, and it was 250 bucks here in Canada. Regular 350.
It is made by ANI out of Italy. It heats the sprayed medium by running air through an internal venturi. There is a dial on the bottom of the handle where you can set the temperature. The warmer you dial, the faster the air circulates through.
As I said it is an air hog, and I had to get a 3 1/2 horse, 60 gallon compressor to power it. My old 1 1/2 horse 20 gallon wouldn't keep up.

The advantage is that the gun lays in a really nice smooth, fairly heavy coat. I have cut down on the amount of coats I have to apply by almost half.

[Mike Ryan]

i have used target waterborne finishes for about 5+ years. I have used them on lutherie and non lutherie and like them. I like the frequent discounts if ordered directly from target.
I use the em6000 but have been tempted to try the em9000 clear poly. I have kind of low end instrument I am going to stain and my try the em9000.
One thing not mentioned.
The finish stays soft a long time. I use the billet aluminum vacuum holder from LMI and it leaves a slight ring dent which is hard to get rid of. I think it takes 3-4 weeks to really harden up, then seems pretty hard to me.
I too have the asturo eco sx gun and 1.3 tip and like it. I don't have a great big compressor but I wish I did.
I really have no luck at all in spraying thick coats. They just run or take forever to try between coats. I look for the first sign of a milky finish and stop a little before if I can.

[Pete Halliday]

Bob, can you provide any more information about your spray booth/box and/or pictures? What size is working, fan CFM, etc.? I'm trying to figure out a good solution for my shop and am interested in what's working for you. I'd also be spraying water-borne so I don't have concerns about explosions or anything. Thanks.

[Steven Smith]

Here's mine. I was going to put a curtain across the front but haven't found it necessary. Fan is in the box, bottom right, and is a 12" explosion proof unit I got off of ebay; it vents out to the roof (had to do that cause my other half said no holes in the brick wall ). Filters going into the box are from the BORG and are easily replaced - just held in place with masking tape. I really like the StewMac Spray Holder, it works great. Drying box will hold 4 body/neck sets. I use a Walcom EGO HVLP gun with the 3M PPS liner system. Air comes though oil/water filters followed by a drier.

I've done 3 guitars with it, two water based and one nitro. It is sooooooooooo much better than my first spray booth.

Here's my old spray booth

[Ron Zentz]

Nice Steven! Thanks everyone for the ongoing discussion on this.

[Bob Gramann]

Here's my spray box. I'm not spraying now, so I don't have it in the window. The fan sits up against an open window and exhausts outside. The vertical part conceals a partition that makes the air path to the filter and the fan about 6 feet long. The overspray is dry by the time it hits the filter. I do not know the cfm of the fan. It is a bit more than a cheap box fan. When I use this, I also use a box fan with a filter in the room because some overspray does escape. I clean that filter later with compressed air.

I planning the next version (4.0) of this in my head. I'm going to use a discarded furnace blower (about 800 cfm, I think) and set it up so it sucks downward from the sprayed object. I want more access to the guitar that I am spraying and less escaped overspray.

[Gordon Bellerose]

My spray booth is built into the corner of my shop, on top of the bench. It is 36 x 36 along the walls, and 46 across the front, and 56 tall.
I have an exhaust fan pointing down, which exits out a wall vent. The fan is a bit small, so I have now bought a new, bigger fan, that will go into the wall at the rear of the booth. I've got to wait for summer to install that.
You can see the holder in the bottom left corner. It is 3/4 inch pipe, and my guitar holders are made from 1 inch conduit.
I have flattened a section 3 inches long on one end, drilled holes in it so I can put screws right into the neck screw holes.
The other end simply slips over the holder.
The holder will swivel both ways, and really works quite well.
After I spray, I hang the guitar on the closet rod above, and close the door. The door has some air openings, which I cover with some cheap furnace filter material, and leave the fan run.

[Dave Stewart]

Another approach to a booth is a knock-down version. I use 2 bi-fold doors (which often show up on big pick-up garbage day) pinned together with big finishing nails, and venting directly into my dust collector (which resides in the closet). Water based finishes only, and the majority of the time it's not needed, it's packed away in the garage.

[Bob Gramann]

I've been tempted by the dust collector but that's an awfully expensive filter to get clogged with lacquer particles.

[Dave Stewart]

Well, my collector filters are just upper & lower bags. I empty & wash them before spraying, then shake them out well after. Nothing will enter them "wet"....the particulate is flour-like by that point (at least EM6000 is). I also use furnace-filter material to pre-filter, which catches a lot of it.

[Bob Gramann]

You may want to reconsider washing those bags. The caked dust helps to filter the finer particles and keep them in the bags. I finally replaced my bags with a pleated filter and got a tremendous increase in flow. My other hesitation to use the dust collector to collect spray is that I want the solvent odor to go outside, not remain in the room. The waterbase lacquer still has a solvent in it that you don't want to breathe.

[Phil Walsh]

Ron, I've used the KTM water-based that LMI sells on my last three, and I've been very happy with it. It gives a lot less blue tinge than other water finishes I've tried.

I've also used both a turbine HVLP system and a standard compressor setup. I lean toward the HVLP because I get a lot less finish floating around in the air rather than on the guitar, which is really the purpose of HVLP. As far as the end result, I can't say there's any difference.

[Ron Zentz]

Thanks Phil. I'm going to try an HPLV turbine unit and I bought the Target EM 6000. Saw a lot of good reviews with that lacquer. I've been very busy at my real job so still not quite ready to finish yet. Soon I hope.