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HVLP clear coat suggestions

 
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jp-90



Joined: 07 Sep 2011
Posts: 124
Location: Austin, TX

PostPosted: Sun Jul 09, 2017 10:24 am    Post subject: HVLP clear coat suggestions Reply with quote

I'm about to clear coat my first guitar since using this HVLP rig. I plan on using Behlens instrument lacquer. Should I simply go at it the same as when using reranch cans? Can I expect to build up finish faster? Based on my experience spraying the toner, I'm thinking that with the HVLP rig, one pass=one coat, as opposed to the usual reranch cans where 3 passes = 1 coat
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Lon



Joined: 30 Dec 2003
Posts: 6086
Location: Stephenville, TX

PostPosted: Sun Jul 09, 2017 1:43 pm    Post subject: Reply with quote

Yes, you will be spraying more volume through the gun than a spray can. I usually set gun for 6-9 inch fan with gun 6-8 away, turn fluid knob all the way out then 2 turns in, checking for wetness on a piece of cardboard or craft paper. I spray the edges first, face, back, then the edges again on the first round. This is where you can gage your speed and wetness. You want a wet coat but not runny.

I usually wait 15-30 minutes between 1st and 2nd round, same between 2nd and 3rd. I'll wait for 2-3 hours before 2nd session, then repeat process. After 3rd session I'll wait over night to flash off good. Then repeat the previous day spraying. I usually do three days of sessions then cure for 30 or longer. That is my finishing schedule that I'm comfortable with.
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Jazzmeister



Joined: 29 Apr 2007
Posts: 1440
Location: The Hawkeye State

PostPosted: Mon Jul 10, 2017 6:39 am    Post subject: Reply with quote

Behlen's is a great product. I've found three wet coats to be adequate, personally. It builds very quickly, especially if you are not thinning it much. I love adding some retarder to help it flow out better, especially when spraying in the heat of summer.
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jp-90



Joined: 07 Sep 2011
Posts: 124
Location: Austin, TX

PostPosted: Mon Jul 10, 2017 8:32 am    Post subject: Reply with quote

Thanks for the tips! I had the gun figured out for shellac and I'm learning I need to open the fluid control way up for lacquer. My first few passes were very light. So far I'm shooting it without thinning through a 1.4mm aircap. Would you recommend thinning?
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Lon



Joined: 30 Dec 2003
Posts: 6086
Location: Stephenville, TX

PostPosted: Mon Jul 10, 2017 11:36 am    Post subject: Reply with quote

Not for a 1.4 mm cap. Anything below 1.0 cap, you would probably have to.
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ladyfinisher



Joined: 21 Feb 2013
Posts: 400
Location: California

PostPosted: Tue Jul 11, 2017 2:26 pm    Post subject: Reply with quote

I always thin it. I don't measure, because it changes with weather conditions. I want it to run off the stick almost like water. Then I have a lot less orange peel to deal with later, but you have to be a lot more careful not to get runs.

I usually spray with that three day schedule also.

Ladyfinisher
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jp-90



Joined: 07 Sep 2011
Posts: 124
Location: Austin, TX

PostPosted: Tue Jul 11, 2017 4:05 pm    Post subject: Reply with quote

Ok, i've got the rig spraying decently. I'm already loving the HVLP setup. I quickly built up the clear coat on the top and bottom of the body with it in a flat position. I've been able to lay it on thick without runs. On the sides I need more passes--I've been more sheepish about runs and have hit the sides with a lot less lacquer as I'm figuring this out.

The new problem is some pretty bad orange peel. I assume this isn't too big a deal until the last few coats? The Jewitt book says to fix orange peel by upping the pressure, but I've already got the regulator (at the gun) reading 20 psi, which is the max for my transtar gun. I assume the heat (spraying in 90 deg, about 45% humidity) is causing the orange peel. Would that make sense?

I'm guessing, as the book says, it's time to thin. Ladyfinisher, do you have a rough idea of the ratio you're thinning the lacquer on most days?
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Jazzmeister



Joined: 29 Apr 2007
Posts: 1440
Location: The Hawkeye State

PostPosted: Tue Jul 11, 2017 4:33 pm    Post subject: Reply with quote

This is where the retarder comes in handy too. Fender used to use it in the vintage era to make the finishes level without tons of sanding/polishing. I start off with about 4:1 for the first couple coats, then go more like 50/50 for the final level coat. Evidently Leo's prescribed method was to even further thin for another couple coats until basically only thinner/retarder was being sprayed. This will also reduce the chances for any blushing. Behlen's is great, but a little thick to spray it straight. I think it should have about the viscosity of buttermilk. It comes out of the can more like 50-weight motor oil.
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jp-90



Joined: 07 Sep 2011
Posts: 124
Location: Austin, TX

PostPosted: Wed Jul 12, 2017 8:23 am    Post subject: Reply with quote

Ok, so what is the difference between retarder and reducer?

retarder -- use when it's humid to reduce blushing?

reducer -- basically a fancy thinner?

Is this right?

I've read a thread or two where someone will argue that you should only thin Behlen SIL with behlen reducer and someone else will say that any decent lacquer thinner will do. I may start by trying kleen strip thinner since I don't want to drive all the way to woodcraft.
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statorvane



Joined: 21 Aug 2003
Posts: 1950
Location: Upstate New York

PostPosted: Wed Jul 12, 2017 6:28 pm    Post subject: Reply with quote

Quote:
retarder -- use when it's humid to reduce blushing?

reducer -- basically a fancy thinner?


Yes retarder is used to reduce blushing. When sprayed, the lacquer can entrap moisture and trap it beneath the surface if it dries too fast. Retarder delays the lacquer drying, allowing the moisture to escape.

And yes, reducer is another name for thinner.
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jp-90



Joined: 07 Sep 2011
Posts: 124
Location: Austin, TX

PostPosted: Wed Aug 16, 2017 5:12 pm    Post subject: Reply with quote

Well, the clear coat went on great. I'm certainly loving the HVLP gun despite the learning curve.

I sprayed a toner on basswood for this guitar, then clear coated. I've only had time to sand at 400 so far, but it already looks pretty good! Solid colors looked awful at this stage. I'm definitely planning on continuing with the usual sanding schedule prescribed around here, but I have a question:

I would like this guitar to have a slightly worn finish. Im not going for a relic look, but I think a fully buffed out finish might look strange. Of course this is easy to experiment with (I can always sand back at a coarser grit), but I was wondering what grit y'all sand to if you're going for a more satin finish?? Or is it always best to let it wear naturally from a glossy starting point?
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ladyfinisher



Joined: 21 Feb 2013
Posts: 400
Location: California

PostPosted: Thu Aug 17, 2017 8:13 pm    Post subject: Reply with quote

I have found it best to go all the way with the finish, wet sand and buff. Then use a super fine pad or 4000 grit sandpaper to take it back to satin. Sounds like a lot of extra work, but it does look better that way.

Ladyfinisher
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RolandR



Joined: 03 Sep 2003
Posts: 8908
Location: Coastal Calif.

PostPosted: Fri Aug 18, 2017 9:56 am    Post subject: Reply with quote

jp-90 wrote:
Ok, so what is the difference between retarder and reducer?

retarder -- use when it's humid to reduce blushing?

reducer -- basically a fancy thinner?

Is this right?

I've read a thread or two where someone will argue that you should only thin Behlen SIL with behlen reducer and someone else will say that any decent lacquer thinner will do. I may start by trying kleen strip thinner since I don't want to drive all the way to woodcraft.
Reducer is similar to retarder but is used when the temperature is hot and dry and the lacquer is drying before it hits the surface resulting in "sandpaper finish".

Usually used in South West e.g. Arizona, New Mexico where the temperature is really hot and really dry, humidity is really low.
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jp-90



Joined: 07 Sep 2011
Posts: 124
Location: Austin, TX

PostPosted: Sat Aug 19, 2017 1:18 pm    Post subject: Reply with quote

Thanks for the tip, Ladyfinisher! I buffed it out with finesse it II and I think I like it enough to just let it wear naturally. You method makes sense, though.

Thanks for further explanation, Roland. Im in Austin, and and even when it's HOT in the summer, the humidity seems to stay at or above 40% a lot of the time, so I may not need it for that purpose. I ended up cutting the lacquer more and more with each coat, using regular hardware store lacquer thinner. I still have a lot to figure out, but the results were way better (and faster!) then I had achieved with cans.

All that said, it is still nice to have a can of clear reranch lacquer around. I've had a couple parts (metal and bakelite) I wanted to put a quick coat on and I'm glad I didn't have to setup/clean the HVLP gun for such a small job.
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