Spraying AKZO Primer

OK I know everyone has heard enough about primers, but I'm just starting to use AKZO and for the most part it seems to be as good as everyone says. My problem is more spraying related and I'm not sure exactly what is wrong with my approach or equipment.

Let me start with I have a Harbor Freight HVLP gun with a guage on the handle. I have a water/oil filter at my compressor so I think the air is clean.

I mixed the AKZO 1-1 as per the directions, waited the 30 mins for the induction time and started spraying. This is the first time I have used this larger HF gun so I had to test spray for a bit to get the atomization right. I finally ended up with the gun guage set at 50 PSI the max for the gun and I was able to get it to work reasonably well, but only for a small fan, maybe 2". I used this for priming my wing ribs and after some initial issues I was getting OK results. If I tried to increase to fan size I wasn't able to get good enough atomization. So I'm just trying to figure out what is wrong. I have a smaller Porter Cable 4 gallon compressor so I don't know if it is just too small for this gun or what's up.

I went to look at the specs of the gun on HF and for the 66222 gun it says 12SCFM @ 45 PSI. I couldn't even find a compressor that would put out that much air. I'm guessing that number isn't right since a lot of people here seem to use these types of guns.

Any suggestions on things to try would be appreciated.

12SCFM is required for constant operation, and it will drain the tank at that rate. Now if you hit the trigger for 6 seconds and off for 24 seconds, that's only a 20% duty cycle and you're only using 2.4SCFM AVERAGE over time. Your compressor can supply that, the trick is that you just need to shoot in small bursts of several seconds length and then let the compressor catch up in between. Try shooting until the compressor turns on then stop, and start shooting again when it shuts down.

The gun settings are pretty sensitive to pressure swings so if you get outside that operating band that it's set for you'll start seeing variations in the spray pattern.

it would seem to me that that teeny tiny compressor is going to drive you nuts .

Needle/Nozzle Size?

What is the needle/nozzle size on the HF gun? Most primer guns are 1.8mm or so. Guns used for topcoats use smaller sizes 1.2 - 1.4 typically. Thicker material normally needs larger sizes. Using one that's too small for the material can give you problems. I primed my entire RV-7 during the build using AKZO and a Sharpe Cobalt HVLP gun with a 1.8 needle/nozzle. I normally shot with around 15-17 psi at the handle and had great results with that. It does sound like your compressor is on the small size for normal spray guns though.

Akzo Priming Gun Alternative

I used a "Critter" spray gun that use pint size canning jars to shoot Akzo. It's basically a large airbrush style gun that is happy with a small compressor. Cleanup is simple since the glass jars rinse easily with solvent...or worst case trash the jar and use another one.
See: www.leevalley.com item # is: 03K03.01

Another advantage of the Critter: you can use a canning funnel to minimize waste/spills when adding the Akzo to the jar, then use a jar lid during the induction wait.

Good luck,
Mike

For me this is what works best.

I have a standard Binks paint gun.

By the book, my primer was rough, dry and too thick.

I live in a drier area. I add about 10 to 20% by volume of regular store bought at OSH, medium straight lacquer thinner. Boy does it go on smooth and stay tough.

Remember if you are going to coat over it with epoxy primer you only have so much time to shoot it. I think it's about 4-6 hours, check your instructions.

Here is what a sample should look like,

http://www.gen-aircraft-hardware.com/toms/rvproj/One%20bay%20outboard.jpg

Scott that is what I'm starting to think too. I didn't buy this compressor for this project, I already had it. Its been fine up until now except for when I'm running my die grinder, but...

Any suggestions on a 120V compressor that isn't huge.

Dan. It has a 1.4mm tip per the HF website.

One other data point. I have a HF detail gun too. I've been using it before with the Stewart Systems primer. I decided to switch to the larger gun since I had so many rib pieces to prime. It also seemed that the tip was clogging all the time. Before anyone say I need to filter the paint I use a med filter from Home Depot Aircraft Supply.

Well I have to bring back this old thread. I got back to priming again and I still don't have the magic mix with AKZO.

First off I did purchase a new Sears Craftsman Professional compressor to get more air. That doesn't seem to have changed my basic problem much though.

So here is a revamp of the issue.

With the HF detail gun I'm able to get a small fan and good atomization, but it seems to clog frequently even though I use a paint filter when I put the paint in the gun.

With the larger HF gun I can get good atomization with a smaller fan, but if I open up the fan it starts to splatter. It almost seems like the tip is too large. Also it seems like this setup is putting out a lot of material. I am able to spray small parts with arrangement, but for larger items like the baffle on the tanks I'd like to get a wider pattern.

Any idea on what to try?

HF guns are great!

Sounds like you are not getting enough air to the tip. Open the valve at the bottom of the handle to increase total available air (listen for the change in air volume with the trigger pulled). Set the gage at the handle inlet at 20PSI - with the trigger pulled. Now you can set the air at the trigger for narrow or wide, and also set your paint amount.
Might try a bit of thinner/reducer to get it to flow out, but make sure the temp rating on the thinner/reducer is correct for the ambient temp.
I have found the AZKO to be an outstanding product. PPG DP(XX)LF is also easy to spray, and the colors can be mixed to get whatever you want. The warbird guys like the Stits green epoxy primer.
Carry on!
Mark

Ray-
I'm also Using AKZO with the HF 20oz. (purple spray gun). I don't think the quality control is super great with the HF guns. I bought 3 of the smaller HVLP touch up guns before I got one I could set & contol "half way". Just for a point of vague reference when spraying wide fans, my 20oz gun is pretty much wide open & sucking a ton of air. I have a kobalt 30 gallon compressor & when I'm shooting wide areas, my compressor is kicking on every 2-4 minutes to keep up.

Mark,

I think you may have touched on my problem. I have been setting the pressure on the gun without pulling the trigger. I thought that was the way to do it, but I was starting to wonder. I'm pretty sure the pressure guage is now reading maybe 10 PSI or something close with the trigger pulled.

The gun has a max PSI rating. I can't remember what it is right now. I am worried that I'll have to turn the pressure up high enough that I will be exceeding the max pressure number when the trigger is not pulled.

I did figure out to open the valve on the bottom of the handle all the way.

Thanks this could make a big difference.

For what it's worth, I have a HF HPLV gun and the pressure on the gauge is set at 65 ish. When the trigger is pulled it drops to about 33 or 34, seems to work well for me. I am shooting a different primer than you tho.