Airbrushing lacquer vs HVLP

[TallDad71]

Has anyone on the forum tried to apply lacquer with an Modellers airbrush instead of a HVLP system?

I’ve tried spraying with a HVLP gun and I’m simply rubbish, orange peel and overspray central! An airbrush would give so much more control but an I right in thinking that no matter how many times I sprayed I would never get the volume of lacquer required for a knock resistant coat?

All thoughts welcome.

[Allen]

Airbrushes are an artist tool that simply will never apply enough product to the surface. Impossible to keep a wet edge that is critical in getting a smooth flat finish.

A automotive touch up gun that is gravity feed would be my recomondation if you can't handle a full size gun. The rest is the product viscosity, gun set up and your spraying technique.

[kiwigeo]

Allen, if possible and if its not giving away any trade secrets could you give us a brief run down on your spraying kit? Guns, nozzles, compressor, filters etc. Thanks

[Allen]

Well, I don't spray lacquer anymore but when I did it was Mirotone 3220 thinned with their solvent and adding about 5% and no more than 10% of Ultra Slow or Retarder to the mix. The last ingredient will make all the difference to your ultamate finish off the gun. I always thinned it more than Mirotone recommended. Certaily 2 parts lacquer to 1 part thinners plus the retarder or ultra slow solvent will go a long way to helping everyone get a more level surface from the gun. 35 to 40 PSI at the gun....not at the guage on the wall. Pressure drop in hoses can be huge.

I use a Automotive Gravity feed touch up gun that is listed as HVLP but honestly I think it's more marketing than anything else. Sold all my really expensive guns to apprentices years ago when I left the trade and now just picked up a reasonably good gun from the local paint supplier. Was abot $300 I believe. No nozzel size listed on it but I'd guess it's 1.2mm or 1.3mm.

I can spray 4 tenor ukuleles and 4 necks easily with the one pot so a guitar will be a walk in the park.

3.5hp compressor and a oil / water trap that is about 12meters from it.

The rest comes down to technique. You can't be afraid of the gun. Practice with just water spraying some cardboard to work out your moves with the correct overlap.

[kiwigeo]

Thanks Allen.

[TallDad71]

Thanks Allen, really appreciate that.

I will have to book myself onto a spraying course I think!!!

[simso]

An old photo which i screen shot from another location,

This is gloss of the gun on final coat, hvlp, viscosity, air pressure, technique, gun type all come into play when painting.

We assume that we can paint as part of the trade, but a painter spends 3 yrs learning their trade, dont be hard on yourself if it doesnt turn out right.

My dad was a spray painter, i painted a few cars before i ever painted a guitar.

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[TallDad71]

Thanks Steve

After spraying five guitars I came to the same conclusion that my main issue was Skill. Without it you can’t get that final gloss coat on the work, so you are back to sanding back and buffing up, hence you may as well slap the lacquer on with a brush!!!!

I’ve just made some lovely Douglas Fir back electric guitars unfortunately for me they won’t take to sanding as the grain is wide and undulating and I like it that way.

[Trevor Gore]

I've sprayed lacquer with an airbrush, touching up the edges of fret boards. It works fine, but you need a big nozzle (for an air brush) and need to spray wet or the lacquer will dry before it hits the target. It's not the tool to use for a whole instrument, though.

I've had an HVLP touch up gun (1.0mm nozzle) for years which worked fine, good atomisation, no orange peel etc., but the fan was a bit narrow and what with broken springs and leaky seals I decide to go for a new gun. I went for a full size one and tried various nozzle sizes but could not get fine enough atomisation and flowout on the job no matter what I tried. Upping the pressure to get the atomisation just meant I sprayed the whole world as well as the guitar. So I've gone back to a touch up gun, which calls itself a LVLP gun, which I've only used once so far and haven't yet dialed in properly, but its clear that there is enough adjustment to get the job done well.

One of the issues with the spray guns I've used (and I'm certainly no expert) is that the controls aren't really independent of each other, so for example if you want to change the fan angle (say for spraying a neck) you have to make other adjustments, too, to keep everything working right. Spraying guitars is a lot more difficult than e.g. spaying cars. To get a good result you need to stay at a constant travel speed, a constant angle and a constant distance off, which is not the easiest thing to do on a guitar shape. All these parameters interrelate, so if you move closer in you have to move faster. But it helps a lot if you have the right tool for the job, which for me (and Alan, it seems) is a touch up gun. Spraying wet and traveling fast seems to give me the best results, but there are too many variables to call that a general rule.

[simso]

Airbrushes are typically .35 or .5 nozzle with a spray pattern width of about 3cm,
A small touchup gun 0.5mm will have a spray pattern of about 7cm
A small touchup gun 1.0mm will have a spray pattern of about 10cm
A small touchup gun 1.2mm will have a spray pattern of about 10-11cm as well

With mettalics you really shouldnt spray with anything under 1.2mm as the mettalic particles cannot be atmoised correctly

A full size gun 1.4mm gun has a spray pattern of about 16cm

Choosing a gun size really comes down to the job, if you have to do10 passes back and forth to cover a surface example an acoustic top using a 0.5mm gun then you will get what we call railway tracks, this is where you look at the instrument side on and it looks like a train track.

If I am painting a guitar or guitar top i will use a full size 1.2 or 1.4 gun, this means the top is coated in three passes.

If i am just painting acoustic guitar sides the a 1.0 or 1.2mm touch up gun are perfect

If i am just painting a neck 0.8 or 1.0 touch up gun is great.

If iam doing decal coverage on a headstock i will use the 0.5 touch up gun, same if I am trying to blend a heel etc.

If i sand through an area and need to add colour, air brush.

Thats my choices

Steve

[kiwigeo]

Thanks Steve and Trevor......very useful information.

[TallDad71]

Still the best forum out there for guitar builders. What an invaluable font of knowledge this place is.

Thanks again chaps.

[simso]

I paint every day of the week, so my setup is way over the top, nothing worse than dust or having to paint something more than once

There are days, where I am spraying uv, nitro, two pack, acrylics, so its not unsual for me to have 4 or 5 spray guns with different paints at any one time.

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[kiwigeo]

LOL......Ive never known you to take shortcuts Steve

[TallDad71]

Steve, what a wonderful space to be able to show off. It must make you smile still every time you walk in.

[simso]

Yep, I am in my 50s and love going to work everyday.

[TallDad71]

“If you love what you do, you’ll never work a single day in your life!”
Glad to hear you’ve reached the pinnacle Steve.

I’m not remotely jealous of your spray booth, my black polythene rubbish bag setup is actually a lot better than it looks, thank you very much!

[TallDad71]

Update:
I had a go with waterborne lacquer and a Fuji HVLP sprayer and worked out that its a lot easier than I remembered. However I went at it with a very low bar for success, I wasn't going to get upset about drips, I had a foam brush to hand, orange peel or even overspray and definitely would NOT be going for wet on wet final coats. I finished up with something that has lots of lacquer on and is the shiniest thing I have ever built.

What did I learn?

I'm on to spraying my third guitar now and I learnt that, as with nearly all stages of guitar building, if you make a cock-up of something you can fix it in the next step. Most importantly it took me about a guitar and a half to be able to start responding to the spray gun itself, faster/slower, closer/further depending on the pattern and the build up on lacquer on the work. Still I find it very difficult to lay on a perfect coat, but I am getting closer and that P800 wet and dry every 3 coats hides everything.

Thanks again for all the advice folks. Ill get there in the end.