And, since I'm at a point where it needs to be perfect (doors, etc.), I'm ba-ack (here asking questions).
Using HVLP system and a solvent based product (Magna Shield from Hood Finishing) and got lots of orange peel. Consistent orange peel. Since I was outside, it may have been the humidity. Maybe.
Turned down the material knob and got stripes (almost dry areas). And, orange peel.
There's definitely a learning curve, but I thought I was over the top (still learning, but having a decent grasp). Hah!
One specific question beyond combating the orange peel and application techniques - is there any difference in technique between a water based lacquer and solvent based?
Anyway, I decided I got nothing to lose to ask y'all for any (more) tips, tricks, etc. Plan to experiment some more to finesse the technique, but, any further advice, knowledge, etc. from folks who've been doing this a heck of a lot longer than myself would be appreciated.
When I have sprayed cars using I have found that too much pressure or too far from the car produced orange peel. I have not sprayed enough cars to master the technique but with the same gun and compressor I have gotten glass smooth and orange peel on different days.
My question is how far away you are holding the gun and how fast you are moving the gun?
As you spray, are you spraying into your own over spray? You should be.
You want the over spray to mainly land on the area not yet sprayed. To do this, the first "face" pass should be along the side closest to you, with overlapping passes until you do the far edge. Before spraying the face, do a pass along all four edges.
Take a look at this, and read all the way through. It might help you understand more about your system. Even the info about the aircaps is there, although called something else they still give you mm sizes for reference.
Stop right here. Do not pass go, do not collect $200. Orange peel only means one thing. You're not getting sufficient paint coverage with each coat. You're putting it on too thin. What's happening is that you are getting spotty coverage with each coat. Think about it this way - you're getting droplets of paint laid down on the surface, with areas between each droplet that are bigger than the droplets. This makes a nice little hill and valley landscape on your project. Then you shoot another coat - still too dry, and some of your paint now lands in those valleys and starts to cover the material a little better, and some lands on the previous droplets, building them up more. This continues until you have the color you want, but this god awful finish. The only address of that at this point is wet sanding the surface flat (not clear of finish, just flatten out the finish), and going at it again.
Now, this time go grab a scrap for some practice. First things first... Set the gun up for an 8"-10" fan. You can easily check the fan by shooting at the scrap from 6"-8" away from the scrap. Get that fan nice and oval shaped, and nice and full in the center with the edges feathering out a bit.
Now the fun part. Get it into your head that you are trying to pull a sheet of that god-awful stuff that the wife keeps in the kitchen for wrapping up food. You know - that clear stuff that guys always get all tangled up and can never seem to get to stick to the sides of a bowl, but women can deftly lay over a bowl and stretch tight. Anyway - imagine you're trying to spray such that you're pulling a sheet of this stuff across your project. Watch as you spray. Don't try to do it by feel or any other craftsman-like sounding way. Watch the spray going on. Keep your head ahead of your gun and watch the spray laying down. Keep your gun dead straight at the project piece and move it straight across the piece, stretching this layer of plastic wrap. You'll know if you're doing it right, because... you're watching - right? Nothing dry. Make it look like plastic. Practice on the scrap to develop the knack and not get runs. Move the gun straight across the project and watch. You'll need lots of light because the overspray, even with an HVLP can obscure your view of the spray. Let your eyes determine your speed. If you don't trust your eyes, you're going to have finish problems forever.
Let the coat flash per the manufacture's directions, and apply a second/subsequent coats. Don't rush it.
Most dry spray (orange peel) problems come from guys who just plane shoot too fast. You can't know if you shooting too fast or correctly unless you're watching the material lay on the project piece. If you practice what I've just written above, you will end up with nice, flat, even coat that flows out smooth.
Oh yeah - one more thing... The only thing more important to keep clean than a woman, is your paint gun and accessories. All bets are off unless you're really, really anal about cleanliness with paint stuff.
SNIP of other great information and timely advice...
Amen... nicely said. When I am SURE the guns and lines are clean, I shoot just a little more solvent through the system one more time.
And make sure your filters are clean. If you don't have filters on your gun itself, you really need them, especially with HVLP. A siphon gun will pick up debris and dirt that doesn't go into the bottom of the paint cup or into the edge creases of cup. But since HVLP is actually pressured, it can push debris into the gun itself. Either way you need gun filters.
Debris in the gun can cause irregular orange peel as it will cause intermittent "splatter" that can sometimes be so fine in nature that it looks like orange peel. Or it can be just plain old splattering in appearance. Old finish (30 days is old to me... 2 years is "aged to perfection" for my amigos) can thicken and cause gelling of the finish that can make consistent spray texture impossible to achieve because you cannot regulate the flow of material, hence you cannot set the pressure correctly for the material.
Personally, I really like the ones on this page. Go a little over 3/4 of the way down and look at the Worthy strainers and click on the links so you can see how they attach, and inside one of the hot links you can see a close up of the mesh and filter itself.
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think too, the underlying message Mssr. Marlow was sending you was to practice, practice, practice. If you are really going to get where you can spray a given finish at any given time under a variety of conditions you have to learn 1) your equipment and 2) your finish. With that in mind, you still have to practice.
Keep good notes of what you have done; record what works and what doesn't. Temps, humidity, time of day, mixes, materials, solvents, gun settings, aircap size, manufacturers of your solvents and finishes.... everything.
Then be prepared for the days nothing works. They are discouraging, but you have to look at them as part of the process as well. But you can help reduce those days dramatically by being bold with with your mixing and spraying by practicing on your scraps, not on your projects.
When I was learning how to mix the NC lacquer I am using now, I went down to the Habitat for Humanity store and bought some spintered door skins. I sprayed and sprayed those skins with different mixes, pressures and aircaps to get what I wanted.
As a sidebar, my worst problem with technique when using my HVLP was not maintaining the proper distance of the aircap to the surface when spraying. After reading and understanding a dissertation from Michael Dresdner on this (which is not that critical with high pressure), I was convinced how critical this part of HVLP was when I saw a stop action photo that showed the fully developed pattern had blossomed 8" from the aircap/gun. Before that, the pattern was not developed; after that, it broke apart.
My solution? Laugh if you want. I cut a 3/4" x 3/4" x 8" stick and put it in my pocket and when I am spraying after a layoff or in a place that have difficult footing or lighting. When I am ready to shoot, I take the stick out (go ahead... laugh) and put it in front of the gun to determine the correct distance. Then I move my gauge and keep the distance as close to the gauge distance as possible.
Search the archives on this forum, too. There is a lot of good info back there on setting up guns, setting up power plants, mixes, etc. No matter how much you think you are screwing up, unless they are (as Mark Twain put it) "disremembering" every single person that does serious finishing has sanded their share of finishes down to start over. Screwing up or unsatisfactory finsihes are just part of this process.
Barry - great link. It has been so long since I have seen anything on the old "wizard" I thought they were gone. Has it been around all this time, or have I got them mixed up with the old "finishing wizard" group?
A lot of good info on that site. Bookmarking for future perusal.
One more point: I learned from a professional sprayer that he ALWAYS sprays lacquer by hitting each surface in both directions. So if you are spraying a door laying on a table spray it back and forth from top to bottom in overlapping stripes. Then move to one side of the table and spray it again from side to side in overlapping stripes.
- This makes sure you get coverage in all the various moldings, nooks, etc.
- This makes sure you don't miss any spots.
- This makes sure you get enough material layed down so it is thick enough to "flow", this is the biggest need to avoid orange peel.
This forces you to use a fairly light spray or you'll put it on too thick.
I've found it really helps and makes things nearly fool proof. Lay down very light coats but you can come back and "wetten" it up with that second coat and slow down just enough to lay it on wet.
Goos lighting is the key to seeing what is happening. Even outsode, shining a bright light across the surface really helps. Pros use "blast proof bulbs". Just be careful.
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