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Plagued by lacquer orange peel3/27/15
I have been spraying lacquer for 15 years in my garage but I have only had consistent success when outdoor conditions are ideal (70+, low humidity). Right now I am test spraying in a 45 degree shop, yeah not the best conditions, but a few weeks ago I sprayed in 60 degrees in my garage on a beautiful day and it was the same result. I am using Lenmar lacquer and a Turbinaire MiniProPlus HVLP system. I have tried everything, every possible setting on the spray gun, every combination of needle/tip/air cap, thinned lacquer and straight out of the can, lower and higher air pressure. Everything results in orange peel when the temperature is below 70. It seems like the lacquer is not properly atomizing. It's coming out of the gun in a fine spatter rather than a smooth mist. I did just completely clean the gun and all of its parts. I have orders for projects almost year round but I have never taken them on in winter because this problem is severely limiting me on when I can do finishing. Any help is appreciated. Thanks
Use a reducer and turn the heat up in the shop.
Probably nothing to do with the spray system, you're trying to get material to flow in a refrigerator. Insulate your garage and buy a furnace! Nothing flows at 45 degrees. Your neighbors must love you.
Well, even at 60 degrees I was having the same problem.
What does it have to do with the neighbors? It doesn't affect them.
you think 60 is warm? Either warm the lacquer or thin it.
"what does it have to do with the neighbors"
How are you venting and capturing the VOC's from solvent borne lacquer?....your neighbors are probably soaking it into their lungs too!
I hope you live in a rural area, on a 5 acre ranch.
You can't even apply household latex paint at 45 degrees!
Add some butyl cellosolve to your material maybe try .5 or 1 oz. per gallon this will release the surface tension and allow flow you will need plenty time to dry before moving to your next step. Good luck!
Up here in Northern Canada, we have a wide range of temps from +90 in the summer to -40's in the winter.
I keep my working shop (I have a 6000 sq foot building, but heat only 2/3 of it with the rest being storage) and finishing room at around 65 F during the winter months.
You have to, after catalyzing the lacquer - thin out to the required viscocity regardless of the amount of thinners you need to add. In the winter I am thinning by approx 1/3, compared to 10% in the summer. I also add a slower evaporating solvent to allow the finish time to flow out.
The other thing is to keep your material stored OFF the concrete - I keep my 5 gallon pails stored on shelving as not to be in contact with the floor which is cold.
You need to heat things up - I would say 60F is minimum to get a decent finish and an extra 5 degrees is even better.
When you turn on the exhaust (I know you are spraying in a garage so Iwill assume you dont have an engineered booth) you will be drawing in cold air so you need some way to replace that heat quickly. I have hot water rads to extra heat to the finishing room in the colder months, and it works great at a constant 64 or 65F.
If you dont know how much thinners to add, start adding more and try spraying. You can see when the spray pattern is a fine mist VS coarse droplets. You should not have to crank the air to atomize the fluid properly either as that introduces more issues..
Forget to add, when you thin this much, you will have to spray one or more "extra coats" in order to have the dry film thickness correct.
Generally for me, I spray one sealer and two to three top coats in the summer to get a 4 mil dry thickness - while in the winter I need to add generally two more since the material is thinned out so much, and you are depositing less solids per coat.
Does butyl cellosolve have the same affect as retarder? I have used that in the past and does it ever take a long time to dry, even with a small amount.
I have heard that thinning lacquer too much reduces its protective properties by lowering the solid content. If this is the case, I guess the question is at what ratio would this happen?
As for the VOC's, how is spraying in the doorway or a garage and allowing the wind to take it away any different than using an explosion proof fan to exhaust to the outdoors? I only have one next door neighbor and none across the street.
Thanks for the tips.
This also depends upon the thing being sprayed, and the operator's technique - it isnt so much an absolute "X number of coats" but the relationship bewteen how much you are reducing the material out of the can, VS how much you need to apply to keep the end result uniform.
Simply put, the thinner the material - the less solids %'age and the more you need to apply to get the same dry film thickness when done.
I use a "blush retarder" to slow down the initial drying. It is the stuff you add in the humid months to allow the water blush to evaporate before the finish skims over. I add a small percentage in the winter to allow the finish to flow out better. Maybe up to 10%. Every manufacturer will know whats best for their brand of finish. It is always best to talk to your rep or the manufacturer IMO.
Man, that is some awful deep looking orange peel. Are you sure you don't have a horrible case of fisheye going on there? Because from the picture that's what I'm seeing.
If it truly is orange peel then the best thing you can do is raise the temps.
60F is really to low a temperature to be spraying. All normal companies recommend 77F (25C) for spraying temps. You can warm up the pc you are spraying in a room, bring it into the spray area and apply your coating and then bring it back into the warm area to dry.
No one has asked, but wondering what your wet film thickness is? Looked at the enlarged pic, and that looks like a really thick coat.
It's just too cold!
Keeping the temps at 77F in the winter, in (I will assume based upon my experiences 20+ years in the business) most smaller shops is not an option in many parts of NA.
Besides being completely uncomfortable to work (my guys find it comfortable around 64/65 which is why I keep the shop at that temp with the finishing room similar) it would cost a small fortune in the months of Dec-March when we have often -30 average temps.
I can attest, since we have been spraying several hundreds of gallons of lacquer a year since the 70's - that mid 60's is just fine for spraying solvent based finishes - if you thin to the proper spraying viscosity.
If you can't figure out the amount of thinner based on spraying experience, then invest in a cup. approx 20 seconds in a Zahn #2 is average for lacquers.
The OP said he is spraying lacquer - I assume solvent based. Water based I have zero experience with and wont offer any advice...
But, based upon several conversations over the years with my finishing manufacturers (I spray a Canadian manufactured post cat lacquer) there is absolutley ZERO negative consequences from thinning the material - and they actually recommend it.
Depositing a few extra, thinner coats of material VS fewer thicker ones, is of no consequence. What matters most is that (a) your finish quality is excellent, and (b) your dry film thickness is what it should be, not too little and not too thick.
In an ideal world we would buy the material, put it into the pot and spray perfectly. In reality, 99% of us have to thin the material out to proper spraying viscosity, and it doesnt cause issues.
Within reason of course. If its 50 degrees, youre on your own! :)
The OP stated he was spraying at 45 degrees in that picture ans also tried it at 60. IME that is too cold to get decent results. The climate here can hit -20 to -30 in the winter and I have never sprayed below 65 degrees. In the winter when we are finishing I may bump the temp up while the finish is curing but never go below 65.You may be able to but if you mess up one big project it can cost far more than the additional heat will.
If you are a high volume shop spraying 8 or more hours a day then it is a cost of business to maintain the temp at an acceptable level. If you are a low volume sprayer then make sure to keep the product temp at an acceptable level and boost the heat only while finishing and then let it cool down after curing.
If you have a legal spray booth you are going to need makeup heat anyway and if you are spraying lacquer in a confined space with no spray booth then you have more potential problems to worry about than the temperature.
The question reveals the answer. You said you get good results at 70+.
Which corresponds with many lacquer TDS.
There's the answer. No mystery. The stuff is too stiff to break up at turbine pressures. And too stiff to flow into a smooth coating once on the surface.
Everyone is on the same page here with excellent advice. You said you see a spatter coming from the spray gun so either your viscosity is way too high or the room is cooling the lacquer too fast. Our spray area temps range from the mid fifties in winter to well over 100 deg and 90% humidity in August so it's never the optimal conditions but we compensate for that seasonally. We use heat only, no solvents, to keep the lacquer flowing - heating it to 145 degrees and recirculating from the gun to the heater constantly. Our piano finish lacquer is also less than 5.0 VOC so it is thick as molasses until it's heated.
This method allows us to spray 6-8mils wet on vertical surfaces per coat with little to no sag or orange peel.
You may want to consider changing your lacquer supplier and method of application for excellent, repeatable results regardless of weather.
Just a thought.
It just isn't the temp of the air in the plant, it also has to do with the temp of the paint, compressed air, equipment and substrate. You can heat your lacquer to 100 degrees but if your substrate is 60 it won't help. I had many of these issues in Wisconsin with furniture, door and cabinet manufacturers. We would make winter blends just for this purpose. The hardest times where spring and fall when the temps would climb 40 degrees from morning to afternoon.
I worked for one shop where we sprayed regular nc lacquer in a heated Devilbiss set up -jacketed hose, warm water circulated to heat the lacquer.
But I was always told that is not good for post catalyzed lacquer as the heat can cause the finish to gel up prematuerly in the hose?
By a blanket heater and heat your material. Granger has them that wrap a five gallon bucket. Or, put the amount you are using into a sink of HOT water. Either way HEAT your material.
The other thing you can do is rub and polish the finish to a satin lustre or high polish. I let the lacquer cure for 14-20 days then light oil sand 180, 240, 360, 400,600 then 0000 steel wool with a little pumice for satin lustre or switch to menzerna compounds and machine buff to high polish
As JeffA said, as soon as the material hits that cold substrate it's done. You could have cold finish coming out and as long as the substrate you are spraying it on is 70F+ then you'll do OK. At 3-5mil thick it doesn't take much to heat or cool the finish. The mass of the substrate is going to dictate the temperature of the finish shortly after they make contact.
I would have to agree that you are spraying at a temperature that is a little on the colder side. Like others have said ideal temps are in the 70's. When you start thinning material to much you end up with other problems like solvent pop. My advice would be to work with your supplier and to try to get your temperature higher some how. I assume with your set up that you don't spray many items. It is also a lot harder to get a finish free off dust and overspray without a spray booth.
If you are using a standard nitrocellulose (NC) lacquer, it can be applied in low temperatures (see attached data sheet). NC lacquer doesn't cross-link so it's not as sensitive to cold temps.
What specific product are you using? There are a couple concerns applying finishes when the temperature is so low;
Catalyzed finishes (pre-cat, post-cat, conversion varnish, 2K poly, epoxy, and polyester) need to be applied when the temperature is relatively warm (use 65f as a guide). And the temperature should not drop below 65 for a few days after the finish is applied. If you use them when the temperature is lower than recommended, they will not cross-link properly and can remain sticky, soft, dull, and fail quickly.
Your spray equipment works best when the finish is in a specific range of viscosity (thickness). For example water is much “thinner” than honey – its viscosity is lower. When it’s cold, the thick finish won’t atomize well when you try to spray it. To fix the problem you just have to add lacquer thinner until it sprays well. You can either keep adding lacquer thinner in 5% increments until the test spray looks good, or you can use a viscosity cup (e.g., Ford #4 or Zahn #2) to actually measure the thickness and adjust it to the right range.
Click the link below to download the file included with this post.