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Yes, from my list of Spraying Fixes I am compiling Orange Peel can be corrected by:Quote:
Originally Posted by Richardwoodhead
Increasing pressure OR Thinning material OR Increase spray pattern OR Decrease fluid flow.
I di dnot want to increase pressure as I was using a HVLP gun at 20psi and wanted as little overspray as possible, I did not know about the other fixes at the time.
Next spray job, in a few weeks I will thin an extra 10% and use decrease the fluid flow a bit.
Gazza, just an idea, but I'd be really interested in the result if you experimented on a test piece doing the following.... increase the air (the guru used my HVLP at 50 psi) and increase the air at the gun. Use a full cone. And move quickly. I think you'd find you get a full even coverage and no orange peel. But it helped me tremendously to SEE it done. You've got to be a little "aggressive" and move confidently over the workpiece.
Good luck,
Richard
Gazza, Mix the lacquer with the same amount of thinners.
Excuse me for butting in guys but I am a paint sprayer by trade and think I can help here. Mix the laquer as per manufacturers instructions and use around 60psi at the gun. Dont worry too much about the orange peel finish as once dry and hard this substrate can be flatted and polished. Use 1200 or finer wet and dry paper on a block and flat the whole area. Dry it and then burnish it with a mild cutting compound. I don't know what makes of compound you have over there in Oz but we use G3 here and then polish to a high shine. If you have a machine polisher it works wonders with a lambswool mop head. Be careful not to burn through by applying too much pressure or not moving the head enough. I would suggest leaving the sprayed article until the next day though to make sure it is completely hard. Also the technique with the spray gun is to fully trigger the gun before the spray hits the surface and move onto the surface and off the other side before releasing the trigger, this avoids build up of the paint/laquer on the edges where it can run. Hope this is of some help to you.
Richard, I will give it a try on a test piece in a few weeks and post here how it went.
Mailee, I am using a HVLP gun and the instructions say use between 20 - 45 psi, I have seen some posts that people are effectiveely spraying with as little as 8psi ??? This is my first spray job so I know nothing other than the million or so posts I have read on the subject.
One of my reasons for buying the HVLP was to use low pressure and avoid a lot of overspray as I don't have a spray booth or anything.
Joe, I think you may be onto something there, I checked this morning (day 4) and the finish is DEFINATELY MUCH FLATTER & SMOOTHER then it was on Sunday. Still can see the orange peel by using a light at a low angle but the feel is quite smooth.
I don't think I have enough material coverage though, it is very hard to tell when applying clear, I have brushed on Poly before and this finish is only a fraction of the thickness of the finished Poly.
Thanks everyone for your input and suggestions.
Gary
Sorry Gazza I didn't realise you were using a HVLP setup. Yes you are right in that it should be around 40 psi. Should get good coverage from this setup. Best of luck.
Thin to manufacturers recomendations.????
Most manufacturers seem to recomend thinning 10%, the manufacturer of the laquer I'm using says " thin up to 30%. ????
I know a number of people who use tha same brand of laquer ant routinely thin 50/50.
It depends greatly on what you are trying to achieve and who's product you are using.
Spraying solid colours as in auto spray painting is an absolute doddle compared to spraying clears & tinted clears on timber.
With timber laquers you should be able to get a smooooooooth coat on the last coat, dust & bugs permitting.
With enough thinners nitro seems to self level quite well with the right amount & type of thinner.
Hi,
I have just joined the forum but have been looking for the last couple of weeks.
My background in in spraying, you guys are on the right track but have missed a few points.
to spray lacquer ( which by the way means its a low solid paint which drys fast but must be applied in several thin coats) as compared to enamels which are high solids which dry slowly and only need about two coats) you have to first of all have these conditions.
1) you must have a gun set up to spray lacquer. The trade term used by gun manufactures is (set up) refering to the air cap, fluid tip and its needle. If you just go to a shop and buy a gun these days most will be set for 2 pack enamels as used by the smash trade. If you use lacquer in them there will be too little paint for ther air coming out of the gun. A lacquer gun has a fluid hole neally twice the size. As lacquer drys so fast most of the solvent is used getting it onto the surface. If you hold the gun too far away the air will dry the paint completely into dust. Each gun manufacturer has a list of set-ups and the paints they are suitable for , a lacquer one usually has a flid hole about 1.8 -2.00 mm an enamel one about 1.2mm.
2) Always thin the lacquer at least 50/50 with thinner and increase the thinner up to 80/20 of thinner to finish. Apply about 5 coats. Usually a sanding sealer is applied first especially to open grain timbers (2-3) coats sand with fine paper then apply the clear lacquer.
3) Leave about 10 minutes between coats or longer, if the temp is below 20 degrees C get the air warm with a heater or sunlight if it looks like rain give it a miss. If the clear goes white stop and wait till the weather improves. You are getting moisture from the air on on the lacquer if you spray over it you will have water under the clear. Don't place a heater especially an infra red one at the timber at it will draw the moisture and air out of the timber and make bubbles in the lacquer.
4) Don't forget air hits the timber before the lacquer gets there so if the grain shows holes when you spray you will be hard pressed to fill them. One of the reasons lacquer was so popular is because of its ability to be "pulled" or treated like french polishing. If you cut with wet paper like a car painted does you get white sludge which is hard to clean away. If you make a pad using a piece of fair dinkum chammois with cotton wool inside to rub the lacquer after its final coat (let it dry completely -24 hrs) you can soften any dry spray or orange peel and move it into the grain holes. As the lacquer drys so fast you just work your way over the area when its gets too soft move on and come back later.
To do this mix 50% thinner and 50% metho adjust the mixture up or down to suit your needs metho weakens the action ot the thinner making it possible to rub the surface and move around the lacquer. Add the mix from the back of the pad wetting the cotton wool and squeezing it through to the front of the chammois. don't have it dripping but the chammios must be wet. Rub in circles, then in figure eights and then straight lines. If you ever wondered how they get grand piano's so good this is how.
You should be able to get a mirror finish, but some people like to pull the lacquer and then spray a flow coat of thinner/clear -90/10 to finish. Pulling over is really good on odd surfaces such as turned legs and other odd shapes.
About actually spraying, wide open fan ( long thin oval) thats like a wide paint brush. less chance of runs. If you close the fan all that paint gets stuffed into a smaller area so you will get runs. Hold the gun about a hand span away and at 90Degree to the surface move at a rate of about a metre in four seconds if you move faster you need to open the fluid control for more, if you go slower close it. you won't get a run if you keep the gun moving and keep the didstance the same. always pull the trigger before surface and don't stop till you get pass the other end. start at the top of vertical surfaces and work down.
Over lap about a quarter of the fan width each time you do the next pass,
On edges spray moving the gun just as you would on a big surface, every second you are onto a dry area, if you go vertically you have to cover the length of the fan to hit dry surface, turn the air cap across ways to do vertical painting of tilt the gun at an angle to you use the narrow part of the fan.
If you still need more info let me know.
Durwood, welcome to the forum,
I will certainly give your ideas a go next spray job in 2 or 3 weeks.
I am realy kean to get it right.
I did find that laquer does not fill any gaps at all (such as poly will).
I also found that you could spot spray in a small area and get quite a built up of laquer and not have it run, seems quite forgiving in that area.
My main proble is Orange Peel finish and uneven application of the laquer.
I have a Porter Cable HVLP Conversion Gun with a 1.8mm nozzle I think.
I kept on thinning until the laquer seems to spray OK (25%), but I think now that more thiners would have been better.
I really have no idea how to set the gun up, I am trying to work it out from what I have read but everyone just says it is different for every job ???
Thanks for your input and guidance.
Regards
Gary
The metho tip sounds interesting.
Hi Gazza,
There isn't any real variation for each job, just each person. depending on who is spraying and how fast they move the gun and how far away from the surface they hold the gun the adjustment is the same. It is supposed to go on as a full wet coat.
Open the fan, turn the material down until hardly anything comes out then keep turning out until you get a full wet coat when you hold and move the gun as you want to. Try it on a test piece and keep opening the gun until you find that it wants to run. Either cut the amount back or move the gun slightly further away.
Lacquer drys by evaporation, which means all the thinner has to leave the coating. Nitrocellulose (duco as its known by its common name) drys within seconds to be dust free and is pretty much hard dry in 24 hours.
If you put on lots all at once, the top drys out and seals off the ones put on before, so do one at a time and let it dry out you can't leave it too long the solvent melts into the previous one to get adhesion. Anytime even years after if you hit it with more the thinner will soften the previous lacquer and melt into it.
If the paint has orange peel its too thick or there is too little or too much air,
you are moving too fast along the panel or you are holding the gun too far away.
If you get a run or the gun drips onto the surface leaving a big blob, quickly wipe it with your finger while its still wet. with a bit of practice you can get it so smooth you can keep spraying and not have to rub the runs.
If you want to see how rubbing the lacquer works. mix some thinner and metho and rub some on to dry lacquer with your finger. do it on a piece of timber with deep grain holes to see how easily you can fill them in.
Let me know how you get on with the spraying, writing instructions is a lot harder than having someone with you to see exactly what you are doing.
Durwood,
Sounds like you have a lot of experience with lacquer spraying. Do you work as a furniture finisher? Reading your advice, I think you operate pretty much the same as the guy who gave me some hands-on help. Enough air and fluid to get full coverage. Full cone of spray. I think this guy used more fluid but moved faster. Probably each operator develops a specific technique within general "boundaries".
It was immensely helpful for me to watch him work. Sounds like watching you in action would be hugely helpful to us spraying novices. I started this thread mainly to encourage other novices to try to get some hands-on teaching with lacquer spraying from guys like you. Spraying produces a beautiful finish quickly. But can also be very tricky if you don't know the pitfalls. Pity we can't arrange spraying seminars and hire guys like you to give lessons.
Anyway, WELCOME and thanks for your advice and tips.
Richard
Durwood, I meant to ask if you sand between coats? You mentioned 5 coats with the 50/50 thinner mix - including a final coat at 80/20 (80% thinner). Do you do a fine sand between coats or just allow the thinner to melt into the previous coat?
Thanks,
Richard
Hi Guys,
No need to sand that just makes dust. the gloss level will go up as you rub. If you want add some retarder to your spray mix especially in the cold weather or hot weather as this help the paint flow out reducing orange peel. Retarder is very slow drying only use a tea spoon per about a litre or it will take days to dry. Its a bit strong to use in the pad for rubbing the lacquer.
I taught at a tafe college for over thirty years these paints were all we had in those days.
Thanks for this helpful post Durwood. A couple of questions...Quote:
Originally Posted by durwood
Regarding 2) above, do you do this with pre-cat lacquer? And do the other points also apply to pre-cat?