taking the big dive to spraying - couple of questions, please!

[Brian Evans]

I'm taking the leap of faith to spraying waterbase topcoat finish. What I have is very similar to endurovar. I have two HVLP pressurized guns, one a small touchup gun with a 1.0 needle, and one a full sized gun with a 1.4 needle. Reading the big thread, it seems people spray this finish with both sizes of both guns and needles, but if one was choosing, which would one choose? Big vs little gun? 1.0 vs 1.4 needle?

Next, I plan to try to achieve a transparent cherry red finish - ES-335 kind of cherry red. I plan to use Transtint type dyes. What kind of mix ratio would you think would be appropriate to start with, and do you build intensity with a stiffer ratio, or with several coats? Last question - this being a single stage finish (no catalyst), how long can I leave finish in the gun? If I plan to spray 3 coats over two hours, can I leave it in the gun? I'm used to spraying two part car paint, and stripping and cleaning the gun directly after every coat. Any tips?

Thanks, Brian

[Gordon Bellerose]

Brian,

I'm Canadian also and cannot get a lot of the oil, or solvent based finishing products that our American friends can seemingly buy at the corner store.
I've never sprayed anything but water-base finish.

I use a larger HVLP gun with a 1.4 tip for clear coats, and most color coats. I only use the smaller gun for sunburst type finishes. It's nicer around the edges.
I find the smaller guns don't spray enough material, in a wide enough pattern to effectively cover a guitar body.
Like most finishes, water-base works best when nice and warm. Think +20 C or better.

The base color coat can be sprayed with the same gun. Alternately it can be wiped on also.
I find it easier to mix my color strong enough so that one coat get you to the tint you desire. This minimizes any grain raising. Sealing bare wood with shellac works well too, but does minimize the effect of the grain under the color.
I almost always use lacquer as a base for the tint. Water tends to leave a streaky or blotchy finish.

I usually spray 3 coats. One per hour, in one 3, to 4 hr. session. I find I can leave the product in the gun for one hour with no issues, as long as I remove the tip and soak it in water in between spraying. I have run into some plugging up issues if I leave it longer.

[Brian Evans]

Gordon, I've just ordered some dyes and such from Wood Essence in Saskatoon, have you used their products? I'm trying a Minwax cross-linked polyurethane called Ultimate that seems to be pretty equivalent to the other high end water-based products out there. Crystal clear, self cross-linking, etc. Actually planning to start spraying some test coupons this week. I'll start with my larger gun.

Brian

[Gordon Bellerose]

Brian, Yes I have used Wood Essence products, and they are top quality.
Jeff over there does a good job of staying on top of his research.

My last 2 guitars have been sprayed with Britetone lacquer, from Wood Essence.
It's expensive but sprays beautifully, dries water clear, and builds quickly so fewer coats are needed.

I have no idea what your level of experience is, so if I am giving you information you already know, please forgive me.

If your wood needs grain filling, do that first obviously. I use epoxy for filling grain. I find it easy to work with and gives natural wood a nice golden hue. It does darken dark wood moderately, but not much more than lacquer does. One of our members here, Todd Stock, has done a nice series of videos on using epoxy as a filler. You can find those on YouTube.
You may want to use a different water-base filler for your finish, depending on your desired result.

Firstly let me remind you that for a translucent finish, STAIN must be used. PIGMENT completely covers, just like paint. (I apologize if this is information you know already)
Your color coat(s) can be applied in a few different ways, depending on what effect you want.
If you want the grain to show vividly, wipe the stain mixed with water, on bare wood.
If you have a curly maple and want the flame to stand out, stain black or dark brown first. Sand it back and then use your color. Again, YouTube has a wealth of info.
If you want a muted grain like Gibson does, seal first with shellac or lacquer, and then spray color coat(s) mixed with lacquer over that. Each successive color coat done that way mutes the grain a bit more because now you are not staining the wood, you are simply covering over the color coat below.

[Brian Evans]

I confess that I am terrified of using stain directly on wood, it seems so irreversible. For this instrument - spruce top, figured maple rim and spanish cedar back - I was thinking I would use the Stew-Mac finishing schedule. Three base coats clear, one or more colour coats, then 5 or six top coats, followed by sanding and buffing. The big deal is to get a uniform colour. I have never been able to get a uniform colour on spruce with hand application, hence digging the guns out and trying spray. I pore-fill the spanish cedar by padding in sanding dust with thin shellac, from a video on the stew-mac site I think. Seems to work well. I have used epoxy as well.

Thanks for your advice, I appreciate it.

[Gordon Bellerose]

Yeah, soft woods need a little different treatment.
Others here will have better info, but as far as I know you have to seal the spruce with either lacquer, sanding sealer, or shellac before staining.
Otherwise it's easy to get a blotchy stain.

[Barry Daniels]

I like to use the term "dye" in place of stain because stain is used to describe a lot of different products and application methods, including dye and pigmented colorants.

[Steve Sawyer]

I like to use the term "dye" in place of stain because stain is used to describe a lot of different products and application methods, including dye and pigmented colorants.

Thanks, Barry. I've been reading Dan Erlwine's book on guitar finishing and he was driving me crazy with this. "Stain" (the noun) in general woodworking is a pigmented product that enhances grain. Dan kept using "stain" and "dye" interchangeably despite the fact that he betrayed the fact that he knows better. Yes, they both "stain" (verb) the wood, imparting color, but the terminology can be confusing to a novice.

A good idea to remember is that stain emphasizes grain because the pigment gets trapped in the wood pores; dye emphasizes figure as it penetrates the wood differentially depending on the grain orientation to the wood surface which varies considerably in highly figured woods.