Questions for users of Behlen Stringed Instrument Lacquer

[Quickstep192]

For those who use Behlen's stringed instrument lacquer - How much do you typically thin it before spraying?

[Howard Klepper]

People get good results with widely varying amounts of thinning, including none. It depends on your spray equipment and temperature.

Get the Behlens lacquer reducer--don't thin with hardware store lacquer thinner. Experiment.

FWIW, I thin 10-15%. But I use a mix of the instrument lacquer and Mohawk (same company) Piano Lacquer, because I find the instrument lacquer somewhat over-plasticized.

[John Arnold]

FYI, Behlen lacquer is the same as Mohawk....Mohawk owns the name and uses it for retail sales. Mohawk is much cheaper than Behlen when ordered direct from the company.

But I use a mix of the instrument lacquer and Mohawk (same company) Piano Lacquer, because I find the instrument lacquer somewhat over-plasticized.

A mix of 30% Piano Lacquer and 70% Stringed Instrument Lacquer seems to be a good ratio. Caleb Smith gave that formula to Mohawk, and you can now order it direct from Mohawk, using Caleb's name. Straight Piano Lacquer is very easy to work with, and builds quickly because of the high solids. But it is susceptible to cold checking and chipping because it hardens so much.
I also thin around 10% to 15%, using Mohawk reducer. I thin more when the temperature is cold, and less when it is hot.

[Quickstep192]

Thanks for the replies. I'll definitely try the mix of piano lacquer and stringed instrument.

I tried spraying the Stringed Instrument Lacquer full strength, then at 20% reduction, then at 25%. It seemed that no matter what I did, I got a lot of orange peel and bubbles.

Long story short...

I decided to "go for broke" and tried a mix that was 50% Lacquer, 43% Thinner and 7% Retarder. It seems to be working. It seemed to spray easily and even though it builds very little per coat, I can probably do four coats per hour.

Is this too thin? Is there heartbreak waiting around the corner? Is it reasonable to think that I'll need double the number of coats that would have been necessary at full strength?

[mirwa]

Orange peel, to confirm this is what we are referring too, have a close look at your car panels. They should not be mirror smooth like guitars are, but the texture of the panel up close gives a dimpled appearance, each dimple is around a few mm wide.

Orange peel is a function of using a HVLP gun, extreme orange peel can also be from gun setup.

Orange peel occurs when the paint hits the panel surface with enough force that it creates a mini fluid wave at the impact point, if you increase the pressure, this impact point has a larger fluid wave around it, same applied if you thin your paint down, its morevisocus now so does not need as much pressure to be sprayed.

if you decrease the gun pressure we also get a reduction in the orange peel.

It's finding the balance

Steve

[mirwa]

Application of paint is a personal choice, using nitro I thin it down 20-30 percent with thinners.

I use a hvlp gun and will run air pressure at around 25-35 psi, I do a mist coat first allow 15minutes and then put on a light coat, wait 30 minutes then put my first full wet coat on, then I allow 30 minutes to pass and do a double wet coat, wait an hr and do a final double wet coat.

Using a LVLP gun, I do the same as above but my air pressure is around 12 psi.

If I want a super high gloss finish with minimal to no orange peel and I have wet sanded previous paint coats and I have no intention of flat sanding and buffing, just straight to buff, then I use a traditional suction fed gun (old school style) I run it at around 60 psi.

Then I let it dry for a few days

Steve

[runamuck]

Orange peel can also be caused by contaminants in the finsih on what ever it is being finished.

[Quickstep192]

Steve,

Can you go into a bit more detail about why the conventional gun leaves a better finish than and HVLP gun? I would have thought that higher pressure would be more likely to leave little waves in the finish. You've definitely got my curiosity up. I appreciate the education.

[phavriluk]

I think that each gun/air supply combination is unique and thinning/reducing/retarding needs to be matched to that particular array of equipment and the ambient atmospheric conditions. I think that everything matters, and everything is involved. Asking me how much I thin will get an answer tuned to the equipment I'm using in addition to including ambient temperature/humidity and my own standards and techniques. And I think this answer won't do the person asking much good,.

I think it would be appropriate for OP to get familiar with the manufacturer's recommendations and practice a whole bunch before trying to finish an instrument. I think whatever technique he winds up using won't be an echo of something one of us says here.

So often a straightforward question gets a reply which includes 'it's complicated'.

[charles Tauber]

Originally Posted by Quickstep192

Steve,

Can you go into a bit more detail about why the conventional gun leaves a better finish than and HVLP gun?

I used to spray nitro with a high pressure gun and compressor. I switched to a low pressure turbine and gun when I switched to water-based finishes, probably 15 years ago.

My experience has been that one can get a good - or bad - finish with either setup, with one not necessarily being better - or worse - than the other.

Originally Posted by phavriluk

So often a straightforward question gets a reply which includes 'it's complicated'.

My experience has been that that is exactly correct.

Based upon what Steve does, his setup, his thinning ratio's, his spraying sequence, I don't doubt that what he says is true. But, that may be different, with different results, for others with different equipment, setup, etc.

[mirwa]

The beauty is to establish a routine with what equipment you have, that routine will always give a better finish the more times you do it.

High pressure guns, give a very fine atomisation, that fine atomisation is extremely wasteful but gives a smooth finish.

Most car painters switched to hvlp guns to reduce toxins in the atmosphere and reduce there overheads in paint wastage.


Steve

[Quickstep192]

So, Here's the thing.

I've sprayed a lot of finish in varying reductions without good results. I'd like to say mixed results, but for the most part, they've been bad results. To be honest, I've had better results using lacquer in a rattle can. Then, I had an epiphany! The stuff in a rattle can is probably heavily thinned and perhaps has a lot of retarder. So, I tried a test with a heavily thinned, heavily retarded mix and eureka! - I seemed to get a good result finally. So, that made me wonder what others were doing. That input will allow me to try different things without abject trial and error so that I may one day have more repeatable success.

I was particularly intrigued by Steve's use of a conventional gun for the final coat. Mostly because I have a good conventional gun, but always thought that because HVLP has higher transfer efficiency that it also meant better flow out. So, I've already learned something.

But back to one of my original questions.

Does 50% seem excessively thin?
Is it reasonable to think I'll need more or less double the coats to get enough build to polish, or is it really some different ratio?

[charles Tauber]

Another variable is that one also needs to match the viscosity of the material one is spraying to the diameter of the "tip" or orifice. If you try to spray thick material through a too small orifice, results won't be great. It might be that you have just discovered that for the orifice/tip size you are using, you need to thin the material more.

50% thinner is "getting up there" for applying bodying coats. If half of what you are spraying is a volatile liquid/mist, then half of it will evaporate, rather than stay on the sprayed surface as film thickness. If that works for you, use what works.

One can use a viscosity cup to measure the viscosity of the liquid being sprayed. The cup has a hole in the bottom of known size and allows you to measure how long it takes for a full cup to drain through the hole, giving you a measure of the viscosity. Sometimes, there is spraying information from the manufacturer related to a specific viscosity cup.

What viscosity to spray depends upon your equipment and the type of finish you are spraying.

[Quickstep192]

Originally Posted by charles Tauber

Another variable is that one also needs to match the viscosity of the material one is spraying to the diameter of the "tip" or orifice. If you try to spray thick material through a too small orifice, results won't be great. It might be that you have just discovered that for the orifice/tip size you are using, you need to thin the material more.

50% thinner is "getting up there" for applying bodying coats. If half of what you are spraying is a volatile liquid/mist, then half of it will evaporate, rather than stay on the sprayed surface as film thickness. If that works for you, use what works.

One can use a viscosity cup to measure the viscosity of the liquid being sprayed. The cup has a hole in the bottom of known size and allows you to measure how long it takes for a full cup to drain through the hole, giving you a measure of the viscosity. Sometimes, there is spraying information from the manufacturer related to a specific viscosity cup.

What viscosity to spray depends upon your equipment and the type of finish you are spraying.

Thanks, Charles

Each of my guns has multiple tip selections and a guide to match viscosity to tip. At higher viscosities, even with the larger tip I was getting poor results. It was only when I thinned a lot and went with a small tip that I got good results.

[phavriluk]

Is OP monitoring air pressure at the compressor outlet or inlet of the gun? Makes a difference.