Lacquer Drying Too Fast
Ambient temperatures and heat from the air turbine may be the reason this finisher's lacquer is drying almost instantly. Here's an extended discussion of tweaking equipment and formulas to moderate the drying time. September 26, 2006
Question
I am a rookie when it comes to spray finishing. But I have decent equipment (Fuji QX4 HVLP) and using a good quality lacquer. As soon as I spray the lacquer on it almost dries instantly. While in a way this is nice, I find it hard to tell where I have sprayed to get the appropriate overlap. I also thought that the lacquer was supposed to flow and level itself over a couple of minutes for a smoother finish. I don't think this is happening if it dries to the touch in seconds. Is this normal or am I doing something wrong?
Forum Responses
(Finishing Forum)
From contributor A:
You may be using too much thinner, spraying the coat too thin, the air temperature may be too warm or you have too much air flowing over the object being sprayed. If you are using a thinner, use some retarder with it also. Usually 5% is a good start. This will work with the too warm situation also. Use a mil gauge to check to see how much of a wet coat you are applying, usually around 3-5 mils wet is what is asked for by the manufacturer. If you are using a fan to get rid of overspray try setting it farther away from the item you are spraying, if you have a booth you may be to close to the fan. If you are using a post-cat product you may be adding to much catalyst and this would cause many more problems than fast drying.
From contributor B:
The VOC compliant coatings that are being used now may not have the same features as you have described. After coating is sprayed, and it dries to a uniform appearance that is what you want, if the final appearance looks spotty, uneven, and not uniform throughout, then you need some help in learning to balance it out. It maybe your gun that needs some adjusting, or you may need some slower additive to improve the coatings flow out.
You need to be very careful about adding any more solvent or any kind of additive into compliance coatings, or they may not be compliant any more. You may want to contact your supplier, or your coating company for advice.
From contributor C:You're using a turbine sprayer. All that "warm" air is drying out your lacquer before it hits the wood, and the air isn't warm, it's hot. This is the reason I quit using a turbine sprayer. I don't spray lacquers but you might want to add some retarder to slow down the drying time.
From the original questioner:Thanks for the responses so far. The lacquer I'm using isn't thinned and the manufacturer says it's formulated for spraying. I've read about the turbine air being warm. The only thing is that the air doesn't feel hot or even warm coming out of the gun - it just feels like room temp. Is that too warm? Fuji recommends an extension hose which is supposed to allow the air to cool more. Maybe I'll try that and some retarder in the lacquer.
From the original questioner:Just to follow up - I took the coupler and air valve off the hose, and the air coming out is rather warm. I don't know if I'd scalding hot, but it certainly is warmer than room temperature. I think maybe I shot myself in the foot by buying the 4 stage turbine too. I always have to get the best and most expensive thing. Maybe it's too much air volume and the air is warm. I'm going to try the extension hoses and retarder and see if that helps.
From contributor D:You could also look into spraying a water based product with your turbine. The water based stuff doesn't seem to have much of a problem with heat. I even warm the stuff up a bit in the frosty cold winter days here in Southern California. Maybe I should buy one of those Fuji units. The Target Coatings USL (ultimate spray lacquer) is a WB product that I use and it works very well, plus you don't have the nasty side effects of the regular lacquer.
From contributor E:I have the same Fuji set up and love it. I do use the 6' whip and I was surprised at how much cooler the air gets just by adding that. To contributor D: The Target USL - can you get that in a pigmented white? I’ve never used it, and I’m just curious.
From contributor F:I have the Fuji Q4 and spray Target Coatings Ultima Spray Lacquer. Great stuff and I've had no problems spraying it with the Fuji. I'm in MS and it's in the 90s every day with high humidity. The dry times have been acceptable. You should give it a try. I don't think Target Coatings markets their USL pigmented directly however, Jeff Jewitt sells it in several colors through his Homestead Finishing Web site. I've never tried the white pigmented, but I'd be concerned about it yellowing.
From contributor B:Water base coatings are not known to yellow, but check it out.
From contributor H:I have the same setup, and I live in San Antonio, TX. Last week it was up around 100, and the week before it was even a little over that which is unseasonably hot, even for us. I refinish doors and entry ways to homes, and was having the same problems. My spray was dry to the touch where I started spraying on a door before I finished one side! The Fuji system is probably part of the problem, but it is certainly not all the Fuji, and there are some workarounds.
One thing I can suggest is to run two 6' whips on your machine, not one. This makes a lot of difference about how hot the air is that actually enters the gun itself. That helped a lot. Try to keep your machine in a well ventilated area, or one that is as cool as possible. Watch for any curves or loops in the hose, and run the hose as straight as possible - certainly the first 5 to 6 feet need to be straight out and away from the machine.
Next, no matter what they say, thin the material. I bought some colder thinner from one of our suppliers instead of the normal stuff, and that helped. Then I add a quality retarder. That made things better since I can get a thicker coat (3 mil or so) on the material when spraying.
I am now storing my finish materials inside instead of outside. The warehouse that I work in sometimes will hit around 115 degrees, and it never occurred to me that at the end of the work day I would be loading the gun with something that was that temperature (ambient air temperature in the warehouse). Even if it was cooler, say 100 degrees, it was much too hot to use. Inside, cooler storage has helped more than anything and I feel like an idiot for not thinking about the high temperatures earlier. The clue should have been that as long as everything is in the lower 90s, the finishes still work fine with proper thinning. My spray schedule is now mostly oriented towards the morning hours.
From contributor G:My lacquer always dries too fast for me. I normally add retarder and that makes it stay wet and melt in real good without getting runs like over-reducing does.
From contributor C:Aren't the whip hoses you guys are talking about slightly smaller in diameter than the reinforced part of the hose? I have a short (3ft) whip connected to a 5/8" diameter hose on an Apollo 1200. The Whip is also rough (corrugated) inside. These two features can reduce the CFM delivered to the gun significantly and should be taken into consideration.
From contributor H:The whips that are sold by the Fuji guys are actually 6' in length (and are sold separately) and are corrugated like you described. I have two on my Q4 (four stage) and there is plenty of air to the gun - air to spare, actually, as I turn down the valve on the air hose about 30% or so even with the two whips on it and it still atomizes my lacquers and polyurethanes fine.
Paul at Fuji told me not to exceed more than 50' of hose no matter what. He was unconcerned with 37' (original hose at 25 ft plus two 6 ft whips), and now after setting it up that way so am I. If I had another system around that I could use to swap hoses on to get it closer to that 50' mark I would just for the heck of it.
But 37' is plenty in the field which is where this gun/system goes to make its living. By the way, I have two guns I shoot with the turbine, a no name with a 1mm cap for stains and toners, and the Fuji with a 1.4mm on it for the finish coats. The no name gun is a bleeder and the Fuji is not. Both are external mix, and both work fine with the longer hose.
From the original questioner:I ordered another section of 25 ft hose yesterday, and it should be here today. I'll let you all know how that works out. I also ordered some retarder for the lacquer too. One thing I didn't realize is the QX4 outputs 138 CFM at 8 PSI. The QX3 gives out 116 at 6 PSI. I saw the Apollo gives out about 96 CFM. So the QX4 is overkill for lacquer. Robert, does the smaller aircap make it easier to spray stains? I have the 1.4mm and it's kind of messy and I don't like how it shoots stains.
From contributor H:The smaller aircap definitely does a better job for me. You can get about the same job with the 1.4 (the stock cap) if you thin your stain enough and mist your coats on. But I have found it much easier to mix the stains thin and mist them on with the smaller nozzle/cap. I get much less overspray and a finer mist as the no name gun has a really nice aircap on it which atomizes really well.
I paid about $110 for the no name gun and love it. Since a new aircap from Fuji was about $60 plus shipping, I decided on this gun as it came with a 1mm and a 1.4 mm aircap and it is really nice gun. What a surprise.
While on that subject, I actually rarely shoot stains anymore. I am using Behlen's line of dyes, and probably won't shoot anything else unless required by the client. I have mix and thinning formulas for my new door installations (new, raw wood) and for my refinishes. The effects of that stuff when thinned and built up before finishing are stunning. They are so clear they make the wood look like it is naturally another type of wood. While some doors are actually Honduran mahogany, most these days are a nastier, Indonesian species. To make it look like the old mahogany we all remember, I am applying a mix of Deep Red Mahogany and American Walnut, then several coats of finish.
Same idea with birch doors except that with the lower grade of birch they use on the doors now, and which I am finding more of, I use the same dye in the lacquer itself. Since I normally put 4 - 5 coats on anyway, I can control the exact color and/or tint, and when I find the color I am after I start shooting clear. Doing it this way took a lot of practice to get it the way I wanted it, but the results are worth it as the grains of the wood don't fill with stain, and the finish never looks muddy. I still shoot the initial coat of lacquer and dye mix with the 1mm cap gun and the lacquer thinned by about 30 - 40%. The following coats are applied with the 1.4mm on the regular Fuji gun.
From contributor F:You should give the Blue #3 (1 mm) air cap set a try for your lacquer and stain spraying. I spray lacquer, stains, WB polyurethane, and shellac with it and it works a lot better than the Gold #4 (1.4mm) set that comes with the gun. I only use the #4 for latex paint and primer. If you haven't already, you should give Paul Smith at Fuji a call. He helped me get everything set up and eliminated a lot of headaches.
From contributor I:Are you using Behlen's alcohol-based dyes? I've tried them on a few small pieces, but found them to be tough to work with. They're very strong out of the bottle and they dry way too fast. Are you thinning and/or retarding them? If so, what ratio of thinner/retarder works well?
From contributor B:To contributor I: Alcohol and Lacquer dye stains are not intended to be wiped or brushed, because they dry too fast for uniformity. These dyes should only be sprayed, unless the pieces you are working on are very small. Lacquer retarder will work, as well as water, to slow the work time down. Start with 5% and then take it from there. Remember, each job you do may be different, so you need to learn to control your workability with the drying time, as both are important to staining.
From contributor G:To contributor H: Are you using dyes on the exterior side of the entry doors? I have always thought they would not hold up??
From contributor B:Pigmented colorants contain larger particles, and would make better UV blockers then anilines dyes. The new micronized pigmented dyes would be a better choice then anilines.
From contributor H:I agree with contributor B - the Solar Lux I am using is not for wiping or brushing unless you are using it as a tint in some other compatible finish. For raw wood (make samples to suit your taste and conditions) I am using one part Behlens, one part alcohol, and three parts lacquer thinner. That was the arrived at after talking to Behlens and many hours and batches of trial and error.
Behlens uses alcohol as a solvent, but it is not pure alcohol. But a little more alcohol (thanks to Behlens for this) keeps it wetter longer, allowing for more penetration. With the additional lacquer thinner in it, it sprays nicely and is easier to get uniform coverage. If it needs to go a bit darker, this mix is easy to touch up or shade. If the day is hotter and I am not getting the penetration I would like, I go half and half thinner and alcohol.
However, if it is a refinish, I only thin with lacquer thinner. Try as I might on a 15 panel door, strip, sand, clean, wipe down, etc, etc., the doors sometimes come out a little blotchy when dyed. I never had complaints, but if it is just as easy to do it right as it is wrong, why not? So I would guess the remaining resins in the wood that stay there after all the refinishing and stripping processes slow down the drying enough.
From contributor J:
I’m getting a little old and easily confused and need some help. (I do remember that 10% BLO in the solvent used for solvent soak makes it work a tad better.) To contributor B: You've always been helpful so here's a question for you. You said here that dyes should be sprayed not wiped. In another post you said that pigmented stains should be wiped not sprayed. Now I've got a bunch of stains in the shop that contain both pigment and oil soluble dye. How should I apply them?
I seem to get excellent results when I wipe on Mohawk's Ultra Penetrating Stain (actually an NGR dye) with a little retarder in it. Nice even color. Have I just been lucky?
From contributor B:
If it was an oil stain – yes, there are many solvents that can be used, but it depends on the type of stain that you will be using. You know, there are stains, and there are stains, and there are finishers, and there are finishers. My reason for mentioning that "pigments need to be wiped", is because paste pigments do not enter the cells of most woods, so if you spray them out heavy with out wiping them they will lay on the wood surface like a paint. That's why I suggest that pigmented stains be wiped on, and wiped off. They can be sprayed, but it takes some experimenting. Most of the two colorant stains can be used either way, if you spray them out, and they dry in the wood, they are spraying stains, if you spray them and they lay on the surface, then they should be wiped dry.
Mohawk's Ultra Penetrating Stains are a hybrid, a different breed than most of the older NGR stains. If you leave out the retarder, they dry too fast to wipe a large surface. As these stains are classified as "dyes" you can see why I say, spray the dyes, and wipe the pigmented stains. But then again, there are oil dye stains, and these certainly could be wiped, but could they be sprayed on with out being wiped off? The answer is, there are stains, and there are stains.
From contributor J:
To contributor B: Thanks for sharing your experience. I guess you're saying things aren't always so cut and dry.
From contributor B:
You know, in finishing, one size never fits all. It’s all about improvising, and having as many options as you know, so you can find solutions for the problems. Not everything in finishing is set in stone. You know that the customer sees the end product, and they don't really know what we have to go through sometimes to get those results. Unless you’re doing the same finish every day, then it can be cut and dry. When you’re doing different kinds of work all the time, you never know what each day will bring. Just be prepared to "THINK".
From the original questioner:
I got to play around with my Fuji yesterday and am having much better results. I ended up ordering another section of the 25ft hose for a total of 50ft. The air that comes out the end is still rather warm, but I wouldn't call it hot. The air that came out of the end was as hot as a hairdryer, and you could really start to feel it after holding it in one spot on your hand.
I also thinned the lacquer about 25% and this seems to help. It is still drying very fast, dry to the touch just after a few minutes. But I am able to get a nice wet coat on the wood before it starts to dry. And the end finish is not much smoother than it was before.
I did order some retarder, but I think that will be the last in the chain. I'm not too experienced with lacquers, but my understanding is that retarding simply inhibits the chemical chain reactions which allow the lacquer to cure? I've heard that using too much can really soften your finish? That's why I think that's going to be the last step. I think I'm going to order the blue cap set next week and give that a try.
From contributor B:
I couldn't let this pass with out asking – you stated "I am using one part Behlens, one part alcohol, and three parts lacquer thinner. That was the arrived at after talking to Behlens and many hours and batches of trial and error." Why would you want to combine these two fast solvents? Sure they both go into one another, but what’s the point? Either of these solvents will do the job, they are very similar in drying time. Do you want to slow it down, or speed it up? What are you trying to achieve?
From contributor H:
My requirements are different from many, so I had to kind of strike out on my own. I am trying to build a repeatable process that I can train others to do, and minimize the chance of failure or a sub-par job. I also have a rigid price model to work in, and that has helped guide the processes that I am developing and currently using. A good product, repeatability and speed are the keys for success for this segment of my business.
That being said, I was looking for a stain/dye/toner/colorant that I could mix in the field and put on a refinished or new entry house door, then immediately come back over with finish.
Here's how I got where I am: Behlen's suggested to go with alcohol, as it would be the best for their product as it would stay on the wood the longest. Longer drying means better penetration and better color saturation. This great, but on a stripped door (again, think multiple panels, up to 15, not a flat slab) there may be areas that aren't perfectly stripped, or the grains on some of the softer woods may have pulled in the resins (think Douglas fir) and they remain in the fibers of the wood. So the longer the dye was on the wood drying and penetrating, it gave uneven results in the areas that my have had resin remaining. It didn't go in as well in the resined areas, and soaked in on the really clean one.
Worse yet, the all alcohol had a tendency to bead up on some of harder to strip and sand nooks and crannies (or even just a soft, porous spot on a soft wood door) that the resins from the original finish had soaked into over the years. It would actually bead into droplets like a very fine sweat. This made a real mess and caused a lot of problems with the re-stripping and sanding of all these areas.
The all lacquer thinner solution was born from the fact that I noticed in earlier tests on my stripped junk doors from past replacements that when I put on dye thinned with lacquer thinner it never had any trouble with beading or penetration. When I thinned the daylights out of it and shot it on in a fine mist it got great penetration and transparency on any surface I used it on. A little more color was not more than another misting of product. The super thin solution helps a lot as it makes it easy to mist on evenly, and the alcohol is so far into solution that it doesn't bead up. But for new wood that is open and porous, this didn't work well as my solution was gone so fast that I didn't get any consistent penetration on the raw wood and it was much harder to achieve consistent saturation. So it was time to slow it down again. Enter the alcohol, and the problem was solved.
I can now produce colors on refinished and new doors so consistent that I have made a wood fan deck of color samples for my lumberyard clients and for myself that has the main colors we shoot on birch, mahogany, and oak.
I wanted to do all I could with the Behlen's as I found it to be the only manufacturer that would even start to claim UV resistance. I need the speed as the price model I am operating under won't allow the time of hand applying a pigmented stain (and then 24 hours more for drying) which might give better UV resistance. I stayed away from the gel stains as it took more time to apply (again, think fifteen little boxes of nooks and crannies, not a smooth slab) and more time to dry. Also, almost all of my clients like the transparent look of the dyes compared to a traditional pigmented stain of some sort. They are used to seeing "real wood" doors on new construction of the better houses here finished with nothing more than a couple of coats of spar varnish with some kind of colorant or maybe just some ambering due to age. Looks great when new, and that is what they remember when they are talking to me after they have been to the showrooms for new doors. When they see the same color and finish sample on the wood fan deck, they know exactly what they want, and what they will get.
From contributor K:
To contributor H: Congratulations on one of the most coherent, complete and well-written contributions ever on these forums.
From contributor B:
To contributor H: As long as you’re making it work for you, that's what counts. If you’re happy, Behlens must be happy.
From contributor H:
To contributor K: Thanks for the kind words. Over the years I have learned a lot on different forums and newsgroups from a lot of different people. I just like being part of and having access to a good community of folks all working together. I am glad to help where I can. And in finishing I think understanding the processes that lead to a procedure are almost as important as the procedure itself. You only get out of these forums what you put in them, so I hope to contribute when I can.
From contributor H:
To contributor B: You sound skeptical. Have your experiences been different with the Behlens product?
From contributor J:
I know Behlens Solar-Lux (NGR) uses premetallic dyes which are more color fast than water soluble aniline dyes. But I always thought their powdered dyes were anilines. Are you using Solar-Lux? If powder, is it also a premetallic?
From contributor B:
To contributor H: No, I use to work for Behlens, and her sister company Mohawk. As long as you’re happy with the results you’re getting, I am happy for you. They may have changed some of their products formula. To me, it was odd that they would use two fast evaporating solvents in their stain. Usually you either want to slow the stain down, or speed them up, depending on the work and size of the pieces that you are staining. All is well, that ends well.
From contributor H:
To contributor J: I use the Solar Lux product, the one that comes in a pint or something similar in size. I buy it at WoodCraft (the chain tool store) for a couple of reasons - the first being that they are the only place in the city I can drive in a buy some, and they aren't any more expensive than buying on the net, and less than the net if you take out shipping. I haven't given their powder dyes a whirl yet as I haven’t really seen a need, so I really don't know anything about them. Also, I don't want to mess around with heating water (they recommend really warm to hot water for dissolution), weighing product/powder with a really accurate scale, and mixing alcohol in it to tune it up. It’s too much hassle and room for error if I am in the field.
It is too easy to crack open the bottle and carefully measure into a mixing container when you use the Solar Lux. I have worked out all my formulas to be easily measured so that all I have to do is pay attention and my "traditional mahogany" will look the same no matter what. I have a couple of sets of stainless measuring spoons I keep to measure the stains, and several different measuring containers for measuring the solvents and finishes.
And I was hugely surprised when I found out how concentrated this stuff is; I should get about 6 - 8 or so exterior doors out of one bottle, two coats of dye sprayed each side. I am not really sure how the actual count will work out as I am still mixing my "custom color" deck, so I have three or four bottles open that I have been experimenting with to make some of the more complex traditional colors. At any rate it is still quite economical to use this stuff.
Taking into consideration contributor B’s follow up post, I indeed did change the formula again today. As it reached 96 degrees today, I went to all alcohol to slow the whole process down as I was not getting the saturation of color and penetration on the raw wood doors I was preparing clear coat. That did the trick though and the nice thing about it is that different thinners or thinner ratios don't seem to change the color of the stain at all.
