I need Spraying Nitrocellulose Lacquer Secret

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Been trying to spray Nitrocellulose Lacquer (Wattyl Stylwood 50%).
I've got an airbrush as well as a small and large spray gun.
Tried the airbrush and got white bloom balls all over it (I believe its talcum powder they use to dull the shine).

Sanded those down and then tried a medium spray gun and got even more the second time.

Currently sanding those down flat ready for the third coat.

Now I've not done much spraying but need to know the secret, is it more/less lacquer or more/less air I need to do?

Do I need to spray from further away?

Peter

[Master Splinter]

White 'lumps' in the spray are often a sign that the paint is underthinned for the gun - too underthinned and you end up spraying cobwebs. Bump your thinning ratio up and see how that goes. (spray some unthinned to see what that looks like, then slowly add more and more thinners to see how the paint sprays out)

You should hold your spraygun about one outstretched handspan away from the surface, and the spray pattern should cover about the same width.

Gun pressure should be about 30-35psi.

[_fly_]

Thank you,
From this information I think I was doing everything wrong.
I was using about 15% thinners in the mix but am spraying far to close.

I'll let you know how I got in the morning..

Thanks again.

[Mulgabill]

G'day Peter!
Brendan Stemp has a YouTube vid that may be of some help to you.

http://www.youtube.com/watch?v=Rj7QJkdycnE

[Scott]

G'day Peter!
Brendan Stemp has a YouTube vid that may be of some help to you.

I was going to say, Brendan's the man to ask.

[Arron]

I typically spray stylwood at 40% thinners. I know that may not be to spec but I've found thats what works for my setup. There really isnt a 'correct' ratio for lacquer - there is no chemical reaction going on like there is with other finishes so its more a matter of finding ratios suitable to your setup and your willingness to do multiple coats. Like Splinter says, you need to experiment - try spraying at 0, 25, 50, 75 % ratios then fine tune from there.

I get a white chalky effect sometimes when things are not right - like a fine chalk dust sitting on the surface. I dont bother sanding this off, just put the next coat over the top and it all melds down somehow - thats the beauty of lacquer.

Here's a couple of other things I've found about Stylwood that might be useful. Firstly, its MUCH better if you use a sealer like Wattyl Rediseal first. Rediseal sands so easily - unlike Stylwood which is a pig to sand. I basically never sand stylwood (unless Ive made a big mistake) I try to do all the sanding and final surface prep on the sealer (I spray one or two coats of sealer) and then do two or three coats of stylwood, trying to get it perfect straight off the gun but not sanding the Stylwood. A lot of flaws that appear in the intermediate coats of Stylwood will disappear with subsequent coats, like those little things like tiny white corkscrews or threads. If some dust falls in the surface or a bug suicides in it then I will often leave it to the buffing stage - although obviously it depends on the size of the foreign body.

Secondly, Stylwood is easier to use if thinned with General Purpose Thinner from SuperCheap. I know thats against company advice but I find it sprays better, levels out better and cleans up easier with Supercheap stuff then with the Wattyl recommended stuff. its about half the price too. Dont try to thin Rediseal with it though, you will need the Wattyl thinner for that or it will gum up.

Arron

[_fly_]

I tried to stay within specs with the 15% thinner.

I've sanded it back to almost smooth so hoping that the extra coats will level it out a bit when I have another go in the morning.

I'll go with Brendans 33% (2:1) mix and start there.
I'll also need to try and work out which knob does what air flow etc.

The Vid helps a lot so I'll watch that again in the morning and give it another try.

Thanks Guys..

[Arron]

I tried to stay within specs with the 15% thinner.
s..

My understanding is that the recommendation for 15% thinners is made to conform with environmental protection regulations and has nothing to do with getting the best result.

Arron

[tea lady]

I was going to say, Brendan's the man to ask.(:secret: or )

[rod1949]

I get a white chalky effect sometimes when things are not right - like a fine chalk dust sitting on the surface. I dont bother sanding this off, just put the next coat over the top and it all melds down somehow - thats the beauty of lacquer.

Jeez I wish I was aware of this awhile back could have saved myself a lot of work.

Thanks
Rod

[RETIRED]

I get a white chalky effect sometimes when things are not right - like a fine chalk dust sitting on the surface. I dont bother sanding this off, just put the next coat over the top and it all melds down somehow - thats the beauty of lacquer.


The white chalky stuff is overspray or in corners a blowback effect that as dried before contact.

This might help you Peter. http://www.woodworkforums.com/f9/lacquers-polyurethanes-485/#post2583


Make sure that you stir it well too. This weather (30+ degrees and 50 % humidity) is not real conducive to spraying either.

You need to increase the volume a fraction. The knob at the back of the needle.

The knob at the base of the handle is for pressure adjustment from the compressor if you don't have a line pressure regulator. Experience counts on this one.

The adjustment knob at the top is for fan or spread. Don't get it too wide or you will get dry spraing at the sides and too narrow will put too much on. Again experience and weather have a lot to do with the size of spread.

[_fly_]

Ta ,

I was going to ask you but thought I'm enough of a pain already.
Knew there would be other guys here that are always helpful.

I'm glad you explained what all those knobs are as the unit I got the other day didn't have any explanation of anything.
You get a schematic but it all says knob for all of them.

I have airbrush, touch up suction gun (good for small amount), and large suction gun (still in packaging) and a gravity gun as well.

One question I still have is can I mix up a batch and just keep it in the spray gun? or do I need to empty it each time and clean it all with thinners every time I'm finished? (I'm guessing this is based on when I'll use it next)?

Do you also do a 2:1 mix with thinners to spray?

Peter

[Master Splinter]

Try these as well...

How to setup your spray gun - YouTube (http://www.youtube.com/watch?v=Sn1WNis5m8k)

How to clean your spray gun - YouTube (http://www.youtube.com/watch?v=oG2nsV-4UkE)

[Cliff Rogers]

Heaps of good info in this thread. :2tsup:

[RETIRED]

Ta ,

I was going to ask you but thought I'm enough of a pain already.No probs at all.
Knew there would be other guys here that are always helpful. Yep.

I'm glad you explained what all those knobs are as the unit I got the other day didn't have any explanation of anything.
You get a schematic but it all says knob for all of them.

I have airbrush, touch up suction gun (good for small amount), and large suction gun (still in packaging) and a gravity gun as well.

One question I still have is can I mix up a batch and just keep it in the spray gun? or do I need to empty it each time and clean it all with thinners every time I'm finished? (I'm guessing this is based on when I'll use it next)?

Do you also do a 2:1 mix with thinners to spray?

PeterI leave the stuff in the big suction gun. The gravity gun I would clean after use as it lets air in.

1st coat is 1:1 thinners and pretty well a dusting coat. 2nd coat is about 1/3 thinners 2/3rds lacquer. Some pieces I leave at that but for table tops or hard wear surfaces I put an additional unthinned coat on.

If you don't seem to have the coverage on the second coat thin about 1/4 thinners to 3/4 lacquer and recoat.

[Arron]

I've sanded it back to almost smooth so hoping that the extra coats will level it out a bit when I have another go in the morning.
..

Another tip is that when you've messed up and have a rough surface or an obvious flaw then you can use pullover to smooth it out. You put a mix of lacquer, thinners and meths in a jar, and use a rag or a rubber to flatten the surface. Just pull the wet rag across the surface. Adjust speed and wetness to get the surface melted and able to be pushed/pulled around. I think its generally better then sanding as less damage is done.

Good for grain filling too.

Arron

[_fly_]

This has got to be the best thread in ages and I only had to ask the questions.
Michael Parkinson watch out, here I come.

Seeing today is a little bit cooler I am going to spray terps onto the spider webs all around the garage door.
That way I can get used to what all the knobs do and work out what knobs affect (or is it effect) what.

Thanks all for the fantastic advice given so freely.

Peter

[Cliff Rogers]

... I am going to spray terps onto the spider webs all around the garage door.....

Use white vinegar instead, the cheap cleaning stuff, not so dangerous.

[Dengue]

Great thread, thanks for sharing all your experiences and preferred methods :2tsup: