Spraying Target USL with Wagner Conv. Gun

[Chris Merriam]

I sprayed for the first time the other day, results were not what I expected, I don't think I was getting good atomization.

Was wondering if anyone with a wagner gun could share their compressor, gun, and thinning steps with me.

I realize every setup and environment is different, but at least I can start with a baseline and adjust from there. I've never sprayed before and have no clue what a good spray setup looks like on the wood.

I had 45lb at compressor and 15 on the gun. I didn't thin the finish at all (i'm in 70 degree basement, humidity not too bad). When I sprayed, the gun pressure would drop to zero, which I think in hindsight is a sign that I wasn't getting good atomization. I also had to unscrew the fluid knob quite a few turns to get product flow.

Does anyone have any settings they can get me started with, and how much if any did you thin the USL?

Thanks for your help!

[Matthew Voss]

Chris-

I don't use that gun but set the regulator pressure at the gun with the trigger slightly depressed (releasing air but not finish). Set the regulator to slightly above the maximum inlet pressure to account for the hose-pressure drop.

[Matthew Voss]

...how much if any did you thin the USL?

Thanks for your help!

That shouldn't be necessary.

[Chris Merriam]

Oh! I never knew when people gave their gun pressures that they were shooting air through them!

Thanks for the tip, I'm going to go check and see how far off I am. Don't get my next batch of finish until friday so can't try spraying yet.

[Larry Fox]

Don't get my next batch of finish until friday so can't try spraying yet.

Could try fiddling with the gun shooting only water (not onto your piece obviously) to get the hang of it - great practice I have found. A lot cheaper as well.

[Chris Merriam]

True, I've played a bit with water but not as much as I should have. My biggest concern was water won't teach me how to set the gun up for good atomization, but now that I think about it, maybe it CAN teach me what good atomization looks like.

I'll work on it tomorrow evening to get ready for Friday spraying.

Thanks!

[Mark Hulette]

Charles Neil suggests spraying cardboard with water tinted with food coloring to practice and setup your gun. Works well.

[Al Navas]

Charles' suggestion works very well! But, depending on the source of the cardboard, the surface may not absorb either water or finish very readily.

What I do, since larger quantity of cardboard might not be available: I bought a roll of brown packing paper at HD, and cut small squares or rectangles to just fit below the exhaust fan. I use it as a target, to adjust the gun. Then I do the final fine adjustments on the gun, also using the paper as target - as the paper is VERY absorbent, the effect of even very minor adjustments can be seen immediately (and no need to add the food coloring):

http://i4.photobucket.com/albums/y136/Sandal_Woods/Shop%20Tools/Finishingroom-spraybooth-1.jpg

I like the brown packing paper because one roll gives me a LOT of it. When used up, I simply throw it away, and tape up a new piece with blue carpenter's tape.


.

[Chris Merriam]

Good idea, I went out and bought some brown paper to give it a shot tonight, and of all things, my air compressor broke!! I think the drain valve bolt sheared off or the threads are messed up or something. Keeps leaking air, going to see if I can get a hold of a new valve tomorrow around town, hate to have to order such a little part.

[douglas hyde]

put a ball valve on it

[Chris Merriam]

Ok, got a new valve today, took some practice passes on brown paper, the drips came out nice and even across the fan width when sprayed vertically.

Then made a few practice shots on scrap plywood, did a cross hatch pattern and measured it with my new mil gauge, it was 10mils! I'm suppose to be shooting for around 2 I think.

I backed off the fluid pressure knob and sped my arm way up, got it down to 3 or 4 mils, not sure how to get 2. Will work on further adjustments later tonight.

[M Toupin]

had to unscrew the fluid knob quite a few turns to get product flow.

Something is wrong... your pressure should be about 12-15 lbs with the trigger pulled. I start with 1 1/2 turns on the material flow to start. Never go over 2 turns. Be sure to use a quality regulator at the gun.

Mike

[Jim Becker]

I start with 1 1/2 turns on the material flow to start. Never go over 2 turns.

Same here...I also start with 1.5 turns and that works well for both USL and SealCoat.

[Chris Merriam]

Thanks, I will work with the fluid knob the next time I'm ready to spray, which will be after I sand :( off the damage I've done.

I've got white cloudy spots all over the place. Read in one of my books if you put WB on too heavy it can do that. So I'm going to sand it all bare and start over again. Was hoping they would disappear in time, but it's been days now. Not looking forward to getting all the mahogany pores clear.

Also, was spraying satin, and think based on some reading that it is better to go with gloss and set the glossiness at the end based on your "finishing" the finish routine. So, I've got a gallon of gloss USL on order now.

Just to clarify on the air settings, so when people say xx at the compressor and yy at the gun, those are with the trigger depressed? I've been going with no trigger, 45 at the compressor and 15 on the gun. It dropped to 5 on the gun with trigger pulled all the way.

Thanks!

[Chris Merriam]

Thought I might resurrect my old thread with an update:

Seeing as how I ignored all the advice about doing a full finishing routine mockup on practice wood, I spent this past week sending my project parts down and getting ready to start the finish over again.

One of my early problems was poor atomization. I tried cranking up the regulator on the gun, but could only get up to 5 psi with the trigger pulled. That sounded wrong and got me to thinking - I probably wasn't getting good flow to the gun. (I have a 25 gallon compressor, shouldn't have a flow problem most likely).

I had been running my setup on 1/4 fittings. I had actually bought all the 3/8 fittings and lines but hadn't bothered changing over. So, I went ahead and changed them out. I also had a little 1/4 air filter, which after reading the specs is what I think my problem was, the cfm on it was way too low. I bought a much larger 3/8 air cleaner instead.

Now I'm getting 12 psi when spraying, still not the 15 most people seem to use, but much better than before.

Resprayed an hour ago and things are looking much better, about to go check now to see how they've dried. I've given up on doing a cross hatch pattern when spraying, it is coming out way to thick. One series of passes with the grain seems to be enough for the moment.

[Chris Merriam]

Another update, to my newbie eye the dried first coat looked great! No bare spots, no orange peel but hard to tell with the open pores of the mahogany. (I'm filling them with the finish)

I dialed the gun pressure down to 9-10 with the trigger pulled, gave a nice even dispersion on the "shoot at cardboard drip test".

Second coat went on very well, though again I didn't do a cross hatch on flat surfaces, and I moved the gun quite fast. Probably covered my 22 inch door in 1-1.25 seconds, but that's all it took to get even coverage.

Also, just remembered, probably another contributor to my previous poor results, I had a coat of BLO on there, and I probably didn't give it enough time to dry and I put the USL right on top if it. This time I put some amber shellac down first, and I also gave the BLO over 24 hours to dry.

I will take some "2nd coat dried" and "3rd coat wet" pictures in an hour and post them.

[Chris Merriam]

Here's some pics of the 2nd coat dry. Took some of the third wet but they came out blurry.

You can see I haven't filled the pores. I'm just going to keep hitting it with the finish til it gets fairly smooth. I've never used grain filler before, not ready to attempt two new things at once.

[Jim Becker]

I'm thinking that you're getting it on a little thick. It doesn't appear to be leveling out. How many turns of the fluid (needle) adjustment are you using? (I generally use 1.5 to 1.25 turns...I put a black line on the knob to make it easy to visually adjust)

[Chris Merriam]

yep, I agree it's on the thick side. I started at 1.5 turns and dialed down to 1.25 or so. It's much better than what I was getting before. Maybe I'll try a bit less, it's just to my inexperienced eye the coat looked a little dry when I went lower.

[Conrad Fiore]

Chris,
Something to think about with regards to filling the grain with USL. At some point after you get a number of coats on, you may notice that the grain is not filling as you anticipated it would. Without using a grain filler, you might have to do some sanding to level the finish back down to the "filled grain" level so that you can spray a level coat. I don't know how much grain you actually want to fill, but if you are looking for glass smooth, sanding will be in order.

[Chris Merriam]

Thanks Conrad, I was beginning to suspect the same thing. Will probably hit it with some sandpaper today and see how it goes. I just put a fourth coat on and didn't notice much difference in the grain-filling.

[Jim Becker]

If you sand to level, it should be with a sanding block, not a ROS. Powered sanding for this purpose will tend to uneven results and good risk of sand-through near the edges.