Spraying Lacquer finish

[Marcus]

Hi All,

Well, the redgum table saga continues after a long delay and I need some help. Long tme viewers of this channel will recall the table is 2.3M long and about 1" thick redgum with the sap holes filled with a black epoxy and all sanded back to 600 grit.

I have decided to go with a finish called "Crodacat 849 - 50% gloss" by Ameron - it's a single pack NC nitrocellulose varnish designed for the professional furniture industry and is very popular. I went out and brought a 13cfm compressor and spray gun, set up the new double garage as a spraying booth (yipee!) and then ran into trouble.

I have now gone through the whole process of sealing the tabletop (with the Ameron 8-800 NC Nitro based sanding sealer) and applying 3 or 4 coats of the lacquer (not to mention several tins of it)but I still get the same result and I am not sure if it is the spraygun (a cheapie), the technique or the material causing the grief.

When I spray a coat, I have to back off the air nozzles that create the vertical fan effect or else I wind up almost powdercoating the surface and the lacquer dries before it hits the table (with or without thinners at 20C). If I back off the air and use the spot spray, the spot is only about 2" wide and by the time I finish doing the table, the overspray has ruined the finish of the first half of the table that has already set. At first I thought the effect was because parts of the table top were not sealed properly and the varnish was sinking in, but the top now has enough sanding sealer to plug the Titannic.

The Crodacat data sheet says to apply a "double header" coat which I took to mean a light spray first with the dispersion nozzles on quickly followed by a heavier coat, though I have tried a number of combinations.

Is it just the el-cheapo spray gun or is there some other trick to doing this that I am missing? Is is better to leave the dispersion nozzles on and slow down the rate of movement to 'flood" the surface?

This table is starting to ruin my life, but the parts that are glossy (not ruined) look absolutely stunning so I want to persevere.

Thanks in advance for the advice all....

Marcus

[RETIRED]

Gooday Marcus.

HOHOHO, been there, done that.

Sorry about the levity but I couldn't help it. http://ubb.ubeaut.com.au/ubb/smile.gif

First off what pressure are you spraying at?

It has to be about 40-50 psi(no I don't know what that is in KP), otherwise you are getting a dry coat. The air actually dries it before it hits the surface.

You spray from the edge nearest you and move away with good overlap on the previous coat. You put as much on as you can without getting runs (experience counts here). Try to get your spray run the full length in one hit. Unfortunately you need a good compressor for this because when you start, you can't stop.

Practise on the bottom first. Between coats we rub back with a Chux scouring pad (a lovely pretty red colour they are http://ubb.ubeaut.com.au/ubb/smile.gif).

Hope this helps. Let us know how you get on.

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Ian () Robertson
"We do good turns every day"

[Marcus]

Hi ,

Well, your advice seems sage but I cannot quite figure out the pressure thing - are you saying that I am spraying with too low a pressure or too high?

I spoke this afternoon with a very helpful chap who recommends some 1200 W&D followed by 1500W&D followed by automotive cutting compound.

I guess with a bit of water and some elbow grease this could work...

Marcus

[bobmundy]

Marcus
You certainly earn points for your efforts with the table. Now we should all realise what it means to put one's heart and soul into something. Just to help with the air pressure - simple rule of thumb is that 700kpa = 100psi's. Thus, 's 40-50psi is equivalent to 280-350kpa.
Hope this helps and we wish you a speedy recovery with the table.


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Bob-
You won't get a second chance to make a good first impression...

[ubeaut]

G'day Marcus

Forget the wet 'n' dry and rubbing compound and try EEE Ultra-Shine. (http://www.ubeaut.com.au/eee.htm) It should fix your problems. It works as a cut 'n' polish on most finishes and should rub out all of the overspray etc. and give you a brilliant blemish free finish. Click on the link for more info.

It has to be good. I make it. Am taking a cubic metre if the stuff To Melb tomorrow for shipping to the US. The yanks reckon it's pretty good too.

Good spraying techniques are an aquired art that takes time and expertise. The best way to learn these techniques is to find a course that will help you, however the next best is to practise, practise, practise, until you have mastered them for yourself. If you canno find a course then try the library, as there are a number of books on finishing that can help, and a couple of good videos from Taunton Press.

You might also find that a jam coat (normal mix with 2-3 times more thinner than usual) used as the final coat will bring out extra gloss and blend in a multitude of sins. Don't spray it too heavy.

Hope this is also of some help to you.

Cheers
Neil http://ubb.ubeaut.com.au/ubb/smile.gif

[RETIRED]

Gooday.

Do you have a pressure regulator on the compressor?

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Ian () Robertson
"We do good turns every day"

[Rod Smith]

Hi Marcus. Lots of good advice above. Next time try using a bit of retarder thinner which slows down the drying a little, reducing dusting and overspray. Good luck. Rod

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[Shane Watson]

Kia Ora ( greetings )
from New Zealand!

Geez Marcus you still having drama with this table. Looks like everyone else has covered it all for you... Plus I don't have too much time to write anything http://ubb.ubeaut.com.au/ubb/smile.gif These internet cafes arn't too cheap you know!

Well just thought I would drop in quickly and let you all know that I am alive and well touring around the great county of NZ!!!

Keep smiling Marcus...!!

Shane!!

P.S. theres always the method of burning the table http://ubb.ubeaut.com.au/ubb/smile.gif

[adrian backx]

G'DAY MATE,......RETARDER WILL SOLVE YOUR PROBLEM ,...BUT WATCH OUT FOR RUNS !!,a double header coat should be all you need and any more than 4 coats and it will craze (crack) in time sorry but i think youve gone a bit overboard now,U should not need to cut and buff, BUT make sure you use 320 grit aluminium oxide paper to sand between coats and remove dust b4 final coat !!....trust me I'm a FRENCH POLISHER !!....cheers Adrian !!.

[durwood]

This thread is one of many in which new spray painters attack a job with no knowledge of what is the correct process.

If the actual steps and equipment required to do the job properly were recorded by themselves instead of being buried in long threads full of poor or worse advice it would save a lot of pain. Is this somehow possible Neil?

First a double header is two wet coats one after the other, the lacquer dries fast the first coat can usually be followed by a second very soon after this allows both coats to stay wet and flow out.

You need a regulator to spray properly as the pressure has to be even not changing as you spray and as stated use about 40-50 psi or multiply by 7 for kpa.

Always spray towards yourself NOT away as this way you can avoid hurting the wet paint as you and the gun and hose will be over a dry surface.If the job is to wide to reach over to the other side spray from the edge towards the middle and then go to the other side and oick up the wet edge andpaint towards yourself to finish.

If the paint is not going on wet and shiny STOP you are only making more work for yourself. Practice on something else until you get the process right not your good work

Rub any dry spray down till the surface is flat and then apply the lacquer

You have to spray the lacquer mixed thin more thinner than paint at least 60% thinner 40% paint. to start then thin even further to finish. You can use retarder thinner but you only ever add a small amount to the normal mixture (5%). Hold the gun about 8 inches away from the surface move the gun at a steady pace. Set the amount of paint coming out of the tip by adjusting the knob at the back of the needle so it ends up on the surface wet.

Normally this is just about all the way out if the lacquer it too wet you can move te gun a little further away from the job and closer if its too dry. Always have a wide fan, don't turn the fan knob in to cut off the flow of air from the horns on the air cap. You need to have a wide fan just as you would use a wide brush to paint a large surface. The fewer passes you make the fewer times you have to pass over the job. If you close down the fan all the paint is forced to go into the narrow area and it will put on a heavier coat (more chance of runs) So wide fan, wet coats ONLY on your job after you prctice on something else ( MDF is good to practice on, being flat and smooth it can be used straight away.) if you have any sealer left put some on first so te mdf waxes don't mess your practice painting.


The lacquer dries fast from the air being used you have to have enough paint coming out to arrive still wet (thats why its mixed so thin, most thinners is lost travelling the 8" to the surface.

If you have 4 or more coats on the job and it can be rubbed flat and smooth only do as Neil suggests -spray with 80% thinner. one coat at a time allow at least 10 min between coats whenever applying (especially if you do a double header)

[maddog 62]

Marcus
hope the info everyone helps you with the table
i make clocks etc out of redgum and like you i am after that perfect finish i know i picked up a couple good ideas
cheers tony

[joez]

Guys you realise this thread was started in 2000? Good advice anyway....

Durwood, i am interested in reading any recommendations you maybe for spray 2pac?


Thanks
Joez