Finish opinion on 7/8th Warmoth body

[EagleTree]

Hello, I purchased one of the first 7/8ths bodies when Warmoth began to offer that option, it's an oldy. At the time, I didn't finish it, I just wanted to test out some sounds using a short scale swamp ash body. This year, I got the hankering to actually finish the thing and had lots of KTM-9 leftover from previous guitars. It's coming out great, but only because I had to punt from attempting to use my HVLP turbo gun and go back to spreading with foam sticks. This was how I'd always used KTM-9 and it's impressive for that. As I get ready to start my next projects, I need to purchase a new can since I've wiped this one out with this build. Since I really would prefer to spray, I'm rethinking my choice.

I know a lot has happened in the last couple of years with Water-borne finishes. I'm hoping that one of those things is that they are more suited to spraying rather than brushing. My KTM-9 seems to have too fine an edge between orange-peel and running, thus I'm not (and likely never will be) suited to spraying it. It seems suited to brushing with it's slow excellent leveling. But on this build, I actually sanded the body back to bare wood twice after making such a runny mess trying to spray. Has anyone worked with SM Colortone, Target or Enduro? Do any of these restore a feeling of control when spraying? For all the millions of threads on using WB finishes, I can't find any where all have been compared side by side and reviewed for the differences in application. If you've used any of these others, let me know how it sprayed in moderate temps.

 

[bagman67]

I'll confess I have no experience with KTM9 or other waterborne lacquer-type finishes, but it does occur to me that if you were using a fairly old can and spraying sucked, maybe your KTM had just exceeded its pot life?


AS with all finishes, your best bet is always to try out the finish schedule you plan to implement on scrap of the same species so you can work out the kinks before you attack your 200-plus-dollars-per-board-foot guitar body.

 

[EagleTree]

I believe it was two years ago I bought this can, I'm looking for the receipt. I hope you are correct, I didn't even think of it and I was loath to change finishes because of how perfectly it levels when brushing. Indeed, there was only a third of a can left when I started this job, so it definitely has had a lot of exposure to air.

 

[bagman67]

Here's what I know about Deft's brushing lacquer:  In order to make it level well when brushing, it contains retarders and flow agent that really render it less than optimal for spraying.  THere may be an analogous phenomenon with the KTM.  You'd want to contact LMII or the manufacturer to be sure. 

 

[EagleTree]

That is a good idea.

I was guessing that KTM-9 may be formulated for brushing. It performs perfectly under that use, I'm loving the leveling that's happening with this baby start. Though as pointed out, perhaps mine was thickened a bit from sitting on the shelf for so long. Not certain the results I had attempting to spray, would lead to that conclusion, but it is possible. I supposed my can could have needed a larger needle to perform correctly (or thinning).

I had heard Enduro tossed around and it's available from a local source, so that was appealing. I was unsure if it would do the same level of gloss though.

Thanks all who responded. If anyone else has tried the others, I have notifications turned on for this thread and will check it immediately.

 

[stubhead]

This is just an "if'n", but was there much sweat and dirt and, ummm... "mojo" soaked into the raw wood? If I was trying to finish that, I would hit it at least a few times with some bleach - maybe 30% bleach, 70% water? And then rinse that off really well, 3 -4 times with a moisty, not-quite-wet sponge. Just sitting around raw wouldn't matter, but human grease & slime most definitely would. It would be easy to see, there would be more where your forearm rests, right-hand fingers dragging over the wood around the high E etc.

If not that, my general rule is really, really thin finish & several coats, maybe 30 -> 60 minutes apart so they'll bond to each other. Runs can ONLY happen if there's too much finish on it. Use less finish at a time - what CAN run? I do like 4 - 6 coats, let that dry overnight, knock down the hairies with 320-grit paper or "plastic steel wool" and then another 4 coats of finish. It sounds kind of simple-minded, but like you say the formulas are drastically better than just a few short years ago. I'd go so far as to say that EXCEPT for historical reenactment nitro & french polishing, the "conventional wisdom" is likely to be WRONG due to being outdated.



P.S. I should preface this (at the end :toothy12: ) by saying:

I am definitely NOT a big voodoo mojo-type "finish guy", and:

I'm quite sure that a lot of the procedural finishing stuff you see "explained" are methods lifted almost verbatim from factory processes for finishing 250 guitars at a whack.

 

[EagleTree]

The reply today reminded me that I shouldn't leave a post hanging like this. I checked with StewMac and they say their color tone is definitely good for spray and recommend their alternate WB product for brushing.

I believe that one of the posts earlier hit the nail on the head about KTM-9. It probably would have been great in my sprayer if it weren't a few years old. The actual project leveled out nicely using the pads to brush it. I will provide photos after it's completely done, but at this stage, the sheen stands up very nicely to my EC Signature Blackie (the only other Black guitar I have). Side by side, the Fender finish looks less wavy, but head on, it looks like a baby version of the Blackie with it's big brother. I'm letting it sit a few weeks before I start another round of rubbing with Maquires Pro 17 cleaner (love that stuff for cutting a shine).

I didn't want to leave a thread casting a dispersion on KTM-9. The temperature may have had an impact too. I was spraying outside of documented parameters (my sister in law pointed that out to me, she's a fanatic about good finishes on woodworking). I think anything over 70 is a risk of orange peel or getting runs from trying to compensate. I'm going to order some more KTM and I'm going to try the Colortone WB too. I have several projects stacked up for this summer.

To StubHeads post: I am going to do some tests with really thin coats when the temperature is right and after I get a new can. When I tried that before, it was very serious orange peel.

A note to anyone who is going to try WB. Use Denatured alcohol each day when you start your next coats. I had quite a few witness lines after I started leveling because I didn't for the last few coats (even with way less than 24 hours drying time), I was getting impatient and assuming I would probably be stripping back and starting over. Fortunately I burned through to the original coats where I had followed my normal prep for the day.

I'll post photos back here in a couple of weeks when I've decided the finish is final.

 

[Cagey]

If you're getting excessive orange peel, you're either not thinning the finish enough, you're shooting from too far away, or the temp/humidity is wrong. You'll always get orange peel to some degree, the trick is diminishing it so you don't have to sand off too much of what you've put on.

The general rule of thumb for lacquer is the Rule of 65: Don't shoot below 65°F, or above 65% relative humidity. Those are limits - don't think that if you're inside them that you're good to go. But, within those guidelines you can play around. You just have to have a sense of how much retarder to use.

Lacquer is thinned/dissolved with acetone (lacquer thinner) as a solvent, which has a boiling point of 130°F. That's pretty low. It means in temperatures that are comfortable for humans, the stuff will evaporate really quick. If you try to shoot from too far away or too lightly, the stuff will literally dry in the air before it hits the target. You end up with a dust finish that you can't do anything with. If you get too close, it'll be too wet and you'll end up with sags and runs that are a real pain in the shorts to repair.

You really want to have something nearby that you don't care about to test your spray gun's pressure/flow before you start shooting the body. Get the distance, rhythm, flow, etc. right before you start on the beauty part. Even a piece of cardboard is better than nothing.

Depending on the temperature/humidity, you can use "retarder" to change the way the stuff behaves. Small amounts. It has the effect of slowing down how fast the vehicle boils off, so you can get smoother finishes in higher temperatures. You might want to read this tutorial - follow it through to the end. Very instructive.