Opinions on Lacquer

[kcasser]

I had been asking this on another post, but no responses. Please help!

Spraying NitroCellulose Black Gloss lacquer with an Earlex 5000. Humidity is about 60%, Temp ~ 26 C. I'm spraying rectangular picture frames about 9" x 12", 1" thick using the circular pattern. Coverage is very good at about 8".

I've read two ways of doing things -
A) Spray, Dry 30 minutes, Light Sand, Repeat

B) Spray, Dry 10 minutes, Repeat (this one doesn't tell me if I should sand after the 10 minutes or not)

Which is it? And, if 'B', do I sand after 10 minutes or can I just spray immediately?

I'm getting very close, but not close enough. I'm still getting tiny pinholes in my finish. I think I need to thin it a little more. I added a good amount of thinner yesterday than what I had used the day before and the finish was noticeably better - but still some pinholes. With the viscosity cup, I understand water should be 10 sec, Lacquer @ 20 sec. I was measuring water at 12 sec, so I thinned the lacquer to 24 sec, presuming I didn't know the proper way to use the cup, but double is double no matter how you measure. Make sense?

Any opinions would be appreciated. I'll be practicing again today at 5 dst. Thank you!!!

Okay, I shot more paint thinned a bit more, about 16 seconds. Same results. Maybe a photo would help. Any suggestions? BTW, no, it shouldn't be dirt. I filter the paint into the cup and tack rag the frame before painting. It just looks like dry tiny specks.

[joe greiner]

I'm far from an expert on finishing, so take this cautiously.

According to my very imperfect understanding, succeeding coats of lacquer dissolve the receiving coat, so sanding is substantially pointless, unless there's foreign matter trapped.

To reduce trapping foreign matter, hang some wet towels in the spraying area. A small fan can provide a light breeze to keep dust airborne, or toward the towels. The breeze can also discourage bubble formation, by forming a local low-pressure area at the just-sprayed surface - similar to the top of an airplane wing. The lowered pressure may pop bubbles from within; this applies to most products, not just lacquer.

Aside from those suggestions, experimenting on scrap is advantageous to establish a spraying protocol, taking notes along the way; which you seem to be doing already

Best regards,
Joe.

[Mollywood]

Hi kcasser,

I no nothing of lacquering but I just googled the problem and found a site you could have a look at.
www.woodcentral.com

The info is in -
Russ's Corner
Finishing Secrets
11. Lacquer.

Apparently direct sunlight causes air bubbles to form in the finish.

Anyway, there's lots of info on the type of finish you are using.

Hope this helps, and Welcome.
I'm a newie too.

[Chipman]

Hi,

I am spraying nitro lacquer at the moment on a turned and carved bowl (Wattyl Stylwood) I have also sprayed steel frames for benches with the black version of it.

Now I don't have a cup or measure the viscosity, but what I have found is that.

You MUST use the correct thinner with your lacquer... check with the supplier
Assuming the frames are wood, make sure they are sanded to 240 grit (or 340 grit)..Apply a light first coat and allow to dry. Then sand lightly to get a really smooth surface (using the first coat like a sanding sealer) and give a very light sand to flatten off any nibs of wood.(fur). Now clean thoroughly and start applying nice even wet coats avoiding heavy build ups that may cause runs and sags. Make sure you allow it to dry between coats and their is no need to sand lacquer between coats. If you don't give a wet coat, the lacquer Will hit the surface as dried up dust and little lumps and when you go over it again you will get a rough surface finish (probably what is wrong with yours) Why not try on some scrap with more thinner, try adjusting the gun and your technique to give a thin moist coat.

If you are getting little pin holes where the lacquer seems to be pulling away (looks a bit like orange peel) you probably have little drops of water from the air compressor. You need a regulator and water filter/trap.

Now once you master this much, you can go to the next stage to get a truly mirror finish... Cut it back and polish it. I sometimes wet sand it back with 800 or 1000 grit and then give it a cut and polish..

Hope this helps,

Chipman

[kcasser]

Thank you all for shedding some light. I've turned down the material volume knob, and that seems to be helping. The coats are coming up a little duller, though, which I think is a good sign. I'll build up the finish and then try polishing it.

Joe, how long would you suggest drying before recoating? I've heard 10 minutes and I've heard 30. Is it possible to leave it overnight and recoat without problem?

Mollywood - thank you for the referral. I'll read more there later. I'm painting indoors, so no sunlight.

Chipman - thinner and paint are from the same source. When you say, "Apply a light first coat and allow to dry", have you used sanding sealer first? Or are you applying that first coat directly to the raw wood? How long does it need to dry for? (It seems to be dry very quickly, but still soft) Then, when "applying nice even wet coats", how long do you let it dry between these subsequent coats? Also, what is meant when you say, "cut and polish"? What does "cut" mean, and what do you use to polish it?

Oh, and I don't have a regulator or water filter/trap. The machine I'm using is the Earlex 5000 HVLP, and there is no air adjustment, and I don't know how to put a water trap in this machine. It's nice in that I have fewer adjustments - the only variables I'm dealing with are - amount of thinner - volume of sprayed material, a knob adjustment - and distance between the gun and the work.

I'm familiar with the "dried up dust" finish, and have gotten over that, I think. I got that when I was using a touch-up gun last year. But these spots appeared in my first wet coat, so I let it dry, sanded it all off and repainted. Again, in the first coat, this is the finish I would get. I've now lowered the volume of material, but I seem to need to be a little closer to the work to get a wet coat. I'll keep practising!

Thank you.

[adrian backx]

I had been asking this on another post, but no responses. Please help!

Spraying NitroCellulose Black Gloss lacquer with an Earlex 5000. Humidity is about 60%, Temp ~ 26 C. I'm spraying rectangular picture frames about 9" x 12", 1" thick using the circular pattern. Coverage is very good at about 8".

I've read two ways of doing things -
A) Spray, Dry 30 minutes, Light Sand, Repeat

B) Spray, Dry 10 minutes, Repeat (this one doesn't tell me if I should sand after the 10 minutes or not)

Which is it? And, if 'B', do I sand after 10 minutes or can I just spray immediately?

I'm getting very close, but not close enough. I'm still getting tiny pinholes in my finish. I think I need to thin it a little more. I added a good amount of thinner yesterday than what I had used the day before and the finish was noticeably better - but still some pinholes. With the viscosity cup, I understand water should be 10 sec, Lacquer @ 20 sec. I was measuring water at 12 sec, so I thinned the lacquer to 24 sec, presuming I didn't know the proper way to use the cup, but double is double no matter how you measure. Make sense?

Any opinions would be appreciated. I'll be practicing again today at 5 dst. Thank you!!!

Okay, I shot more paint thinned a bit more, about 16 seconds. Same results. Maybe a photo would help. Any suggestions? BTW, no, it shouldn't be dirt. I filter the paint into the cup and tack rag the frame before painting. It just looks like dry tiny specks.

G'day mate !! I dont know what an EARLEX is but "I love my name is earl !!",your problem is your lacquer is too thick, try using a retarding thinner for nitro lacquer !! and if your picture frames are made of MDF they MUST be sealed with an appropriate sealer at least 2 coats (cut back with 320 grit aluminium oxide paper NOT GLASS PAPER )no real need to thin lacquer any more than 5-10%, a conventional gun with a 1 litre pot 3/4 full lac>1/4 thinners,could also be the tip is too small on the gun !!,Retarder will slow your drying time but let the lacquer flow out easier (also stops chilling in cold weather & blooming in humid),you must sand between coats especially 1st & 2nd,remember GOOD PREPERATION =EXCELLENT FINISH !! and if you want a mirror finish you must cut and buff !!,......Trust me I'm a french polisher with 30 yrs experiance !!......CHEERS ADRIAN.

[kcasser]

G'day, Adrian!

Earlex is an HVLP system. You can see it athttp://www.woodcraft.com/family.aspx?familyid=20047, if you're curious.

The wood is Poplar. It was primed and lacquered by an experienced lacquer painter, but he left some nasty dribs on the frames, probably from fingermarks, and my customer rejected the job. So, I'm trying to do better

The tip is 1.5 mm. What means 'cut and buff'? What do you buff with?

Thank you for your help!

Ken

[adrian backx]

HI, Ken Cut and buff = sand with wet and dry 1200. 1400 then buff with buffing pad on drill or arbour using cutting compound (panel beaters ) until desired gloss is obtained (bit of an art) buff speed needs to be about 800rpm or you will burn the finish !!, but if you want the picture to stand out then dont bother !!or your eye will be drawn to the frame !!......AB.

[adrian backx]

Oh and THE HVLP OFF they are USELESS !!, a conventional gun sprays a lot better !!> IWATA W77 is my choice of weapon !!.....

[kcasser]

With all respect and appreciation for your advice, I'm hoping there are other opinions on the HVLP since I just spent US$325 plus US$75 delivery to get one. I didn't have any luck with the conventional sprayer the last time I tried this project, so I thought HVLP would be the way to go. So far I'm happy with the rig. I just have to find the right combination...

[kcasser]

Adrian,

I hope I didn't tick you off with my last comment. I only hope I can salvage what I'm doing! I found this site too late in the game, but I am determined to learn this craft so that I can add it to my bag of tricks.

I took your suggestion and used a larger needle and turned down the flow, I added a bit more thinner and some retarder. It's getting better.

I'll try more tomorrow. For now it's time for me to go.

Thanks!

Ken

[Chipman]

I am not familiar with your sprayer, I use an air compressor and conventional spray gun. Cut and polish was explained by an earlier post. 1000-1200 wet and dry paper to give the lightest of sandings (water and a little detergent) then use a cutting compound with a wax in it and buff it up (eg kitten cut and polish or swirl remover). For small jobs, I just use a soft cloth and do it by hand and get an excellent finish (follow the directions on the container)

From the further info you have given, it seems like you need more thinner... Light coats and let it dry between coats (about 20 minutes depending on the weather) If you are going to sand heavily it would need to be left over night (My job from last night came out great... 6 coats of lacquer, just needs a light cut and polish now...will do it tonight)

Chipman

[joe greiner]

I'll defer to Chipman's more enlightened experience about timing. Like I inferred, I'm flying half blind here. Anywhere from 10 - 30 sounds about right, though, and overnight for sanding.

On a just revived thread ( http://www.woodworkforums.ubeaut.com...read.php?t=457 ), Neil (UBeaut) suggests EEE-Ultrashine for polishing instead of rubbing compound. Now known as simply Ultrashine because some of the upover gang didn't appreciate the pun (although I really liked it!). Penn State Industries is the Oosa distributor: http://www.pennstateind.com/

Interesting low opinion about HVLP. I had the impression it was the duck's 'nads. At the moment, all I use my compressor for is filling tyres and occasional dust clearance, so need more research before I take the plunge.

Joe

[kcasser]

Thanks, Chipman! Yeah, a bit more thinner seems to have worked wonders. I'll know more later tonight when I try again. It's confusing because in one place I read to use 60% thinner, 40% lacquer. Adrian suggests 5-10%, of course then he said 3/4 lacquer and 1/4 thinner which seems more like 25% to me, but anyway, I think I'm at about 50/50 right now. It's also been suggested to use a thicker tip, but wouldn't that give me a heavier coat? I tried it but really couldn't sense much of a difference once I had it thinned enough.

Joe - EEE - it took me a while to get it, but I understand the pun

Regarding the HVLP, we really only have one negative opinion on it. I'm sure Adrian knows his stuff, and it does seem like everyone else is using a conventional gun, but I will say that I've been very happy with the unit. I like not having to deal with adjusting air pressure and air flow - it takes those two variables out of the mix. Also, it's really easy to clean and seems very well constructed. As mentioned, I tried lacquer before with terrible results using a conventional gun, but, it was only a small touch-up gun which may have been part of the problem. And, I knew much less then than now, and may not have thinned it enough. Also, I was working in an open garage where there were breezes blowing through causing the lacquer to dry prematurely. If I were to do it over, I would probably follow Adrian's advice and pick up a better conventional gun. It would have been cheaper since I already have a huge compressor here at work, and it probably would have been easier getting qualified advice. Oh well, I have what I have and I'll see it through to its conclusion. I'll let you know how we make out.

Thank you everyone for your support and advice.

Ken

[kcasser]

Joe,

I just learned one plus for HVLP - you don't need a water separater because HVLP eliminates the heating and cooling of the air stream. In a conventional system, the air is heated by the compressor and pushed into a tank. It cools down in the tank. Then, you go to spray with it and the air can be cooler than the dew point causing condensation on the work. HVLP blows the air directly from the turbine and it comes out warm all the time. There's no chance for it to cool before spraying so it stays dry. Very interesting.