Spraying SW all purpose oil based enamel - not drying beautifully - why?

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Old 02-04-14, 06:45 PM
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Spraying SW all purpose oil based enamel - not drying beautifully - why?

I'm painting a piece of furniture using SW all purpose oil based enamel paint. This was bare wood when I started. What I've taken a picture of is about the 4th coat. I'm trying to figure out why when this pain dries, there is a modeled look. It's not a smooth, uniform sheen. I'm beginning to wonder if it is because I thinned it for spraying. It sprays and covers very well. I sprayed the top of this furniture(pictured) and when I was done, it was a thick, shiny, uniform coat. But, as it dries, it gets this uneven look to it. Odd.

The reason I suspect it is the thinning of the paint causing this is because the runs down the side of the can (also pictured) are perfect when they dry.

I used "Kleen Strip" brand "odorless mineral spirits" to thin the paint. I didn't thin it too much, just a little, so it would spray.

Thoughts?



 
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Old 02-04-14, 07:26 PM
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I'd be willing to bet that its the grade of paint thinner you chose. It probably affected the flash time of the paint and caused an uneven finish as the solvent evaporated out of the paint.

You probably would have had better success thinning your paint with a high quality solvent such as Kleen Strip VM & P Naphtha. It evaporates out of the paint more quickly, which is probably what needed to happen.

I've got a bottle of some other brand of "green" paint thinner. I was quite surprised one day this winter when I went to the truck to grab it and it was frozen solid. Moral of the story: Obviously not all paint thinner is meant to thin paint!
 
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Old 02-04-14, 07:32 PM
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That's what I was thinking too. I just wanted someone who knows what they're talking about to agree with me. I have some Naphtha, I'll mix up a new batch and spray a coat. thanks!
 
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Old 02-04-14, 07:43 PM
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You will have a hard time getting rid of that dimpled texture in the paint, even if you recoat it, that texture will probably still telegraph through. But it should be a vast improvement over the current finish.

I'd give it a good sanding with a fine grit sandpaper before recoating.
 
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Old 02-05-14, 04:19 AM
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What prep/primer did you use? what type of spray equipment are you using?
 
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Old 02-05-14, 05:21 PM
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Well I'll try to respray tomorrow. We had an ice storm today and the power has been out all day!

I didn't use primer because I have to distress and sand through the paint in certain spots and the primer wasn't black. The darkest I could get would have been gray and that wouldn't do.

I'm spraying with Graco spray station 900. cheapy Lowes outfit but it works rather well for a $100 spray outfit.

Let you know how it turns out and take pictures too. Thanks!
 
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Old 02-07-14, 02:53 PM
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BEAUTIFUL!

I cleaned the spray out and made up a fresh bath of paint. Thinned it just enough using naphtha and it dries perfectly! Also, I think it dries faster too. Maybe I'll post up some before and after shots of this furniture when it's done.

Thanks again!
 
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Old 02-07-14, 07:08 PM
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That's good news! Thanks for the update!
 
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Old 02-07-14, 07:15 PM
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I take that back - darnit

Well, this is weird. (3) small door trims and (2) drawer faces painted perfectly. Actually, I first tested this by painting only one of the two drawer faces. I just wanted to see if it would fix the problem. It did. The paint dried perfectly. So, I painted the whole project, the other of the two drawer faces and (3) door faces. After that, I sprayed the top of the furniture piece and the sides. The top and sides have the modeled pattern on them. UGH!!!! The only thing I can come up with that I did differently is that the drawer faces and door faces were painted with a round fan pattern from the sprayer and the parts that are messed up were done using a vertical fan pattern from the sprayer. Fair enough, I'm using a budget sprayer but still.... this is odd.

Paint is paint - if it was all mixed the same, shouldn't it all dry the same?
 
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Old 02-08-14, 05:21 AM
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It has to be in the spray application. What puzzles me is you said the round fan came out good but the straight fan didn't - it should be the opposite. Are you keeping a wet coat all along or do you think some of it might be tacking up and having overspray dry on it instead of melting in. Is the paint being applied heavy or wet enough?
 
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Old 02-08-14, 05:42 AM
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Seems like the paint is heavier on the fan pattern. I notice that when I use the round pattern for small stuff, I turn the nozzle pin adjustment way, way, way down so that I get only a little bit of paint and I have amazing control - almost so good you don't have to tape. However, when I rotate the nozzle to a vertical fan for the large flat areas, hardly any paint comes out at all so I've got to back off the nozzle pin adjustment to allow more paint to flow. I don't notice anything tacking up too quickly as I spray fairly fast. The only thing I can come up with is that I'm applying too much paint when I'm using a fan pattern. Maybe it's going on too thick.

This morning I'm going to hit the top of it with 220 grit to knock down most of the paint, then smooth it with 320, then spray the top with the round pattern exactly how I did the pieces that turned out well.

Once I mix up paint and thin it for the sprayer, if the sprayer sits overnight, I don't have to re-thin the paint right? The thinner can't evaporate out of the paint spray hopper right?
 
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Old 02-08-14, 06:00 AM
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It's best to return the paint to a sealed container if it's going to be unused for an hour or more! The paint in the cup might be ok but it's apt to dry here and there in the gun causing problems when you go to spray. To play it safe, I'd strain the paint and clean the gun before resuming painting.
 
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Old 02-10-14, 10:43 AM
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I'm tearing out what little hair I have left! UGH!

Ok, since I've already spent about 3 times the amount of time I should have on this project, I figured, why not do a little experimenting. I switched sprayers all together. I'm using my compressor and a siphon-feed cup sprayer. I was able to get a very fine mist, very well atomized spray from this sprayer so I thought for sure it would do a better job. Well, while it sprays nicer than the $90 lowes sprayer, the paint is still drying unevenly. What I notice is on the top surface, there are lines which are darker than the rest of the paint. It's a rectangle shaped top and I'm spraying shortways back and forth. Nothing special, just spraying the same way I spray lacquer - back and forth, off and on and a little overlap. Once I was done spraying, the entire top surface looked glossy, wet, deep and even. Once it dried though, it wasn't even at all. Like I mentioned, there are passes which are darker and have more sheen.

Maybe the sprayer isn't set up right? Honestly, I'm so sick of this project at this point I'm ready to just roll the paint. I just thought I could get a really nice, factory-type coating by spraying.

How do you all set up your sprayer with paint? When I set up a sprayer for lacquer, I open the pin nozzle all the way and back off the fan screw all the way. Then I back the air pressure all the way down and increase it incrementally until I get a nice, atomized spray. With this sprayer however, it's almost backwards. I have to have the pin nozzle almost all the way shut or this thing puts out some SERIOUS volume. Air pressure is around 20psi.

 
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Old 02-10-14, 02:39 PM
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I rarely spray with conventional gun at pressures less than 25-30 psi. Depending on the material being sprayed I might even double that air pressure. I usually set it about 40-45 psi for oil base enamels but a lot depends on the gun being used.

Is the paint coming out of the gun evenly? It kind of sounds like it's 'fingering' - shooting more paint out at the edges of the fan.

Once I was done spraying, the entire top surface looked glossy, wet, deep and even. Once it dried though, it wasn't even at all
that is very confusing normally if it looks good wet, it will look good when it dries.
 
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Old 02-10-14, 05:29 PM
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I agree... sounds like what mark calls fingering. My sprayer will tend to do that too when the material is thick. I will usually turn the fan so that it sprays diagonally at a 45, not at a 90. On large pieces, I'll often spray left to right then up and down to try and hide any "fingering".

The lines are showing up because you aren't spraying an even mil thickness on the entire work piece... its thicker where its "fingering", thinner where it is not. IMO you should go back to the round spray.

If you have 3 adjustments on your gun, you might need to play with the air volume adjustment (usually above the material metering valve). Some guns have an air pressure regulating adjustment on the bottom of the handle. You will need to test the settings on these valves by spraying some paint on some cardboard until you reduce the heavy fingering on the edges. But spraying at a 45 may also help some.
 
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Old 02-13-14, 11:07 AM
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Thanks again. Who would have thought spraying paint was so complicated?

I finally gave up and brushed the piece. It looks very nice. I will indeed be revisiting the sprayer setup in the future when I'm less pressed for time. At that point, I'll mess around a BUNCH before I do any actual painting.

You all are awesome.
 
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Old 02-13-14, 12:30 PM
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While spraying looks easy, it's more complicated than it appears. Besides the skill needed when pulling the trigger [and that comes with practice] you have to have the right spray equipment for the material being sprayed and then have it at the proper consistency. When problems arise, it often takes spraying experience to find and fix the culprit. We can help some but can only do so much when not there to experience the issue in person.

Glad it came out good in spite of all the issues
 
 

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