Mottling/stripes silver base

Creativename

Creativename

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This is my second time redoing a hood off of a 99 suburban. The paint code is WA382E and It's omni plus with mr186, I'm using a ws 400 evo 1.3 at 29psi, and It was 70-80 degrees both times. I'm about 3-3.25 turns in on the fluid, the fan was open, and the pattern looked fine when I tested it. I gave it 10 minutes flash time between coats and it wasn't heavy at all. When I tried a drop coat it just looked kind of blotchy and cross hatch didn't seem to really affect it.

I feel like I'm beating my head against a wall with this. I talked to the paint store about it and they didn't really have an answer for me.
 
You've got several issues from reading your post. First mottling in basecoats is a symptom of spraying too wet. Striping is a symptom of improper overlap. Improper overlap can result in mottling if you are double coating an area because you are inconsistent in your passes. Your issue is one or both of these things. In addition MR186 which is a medium reducer is really too fast of a reducer to use in all of but the coldest temps (60-65 degrees)
Also the Evo is a clear gun more than anything. It is not going to shoot silver metallic very well unless you throttle it down quite a bit. 3+ turns out is way too wet. When you spray base you only want to spray in at most medium coats. Try 1.5 - 2 turns out (max) and a 90%-100% full fan, to start with. Concentrate on 50-75% overlap each pass. Concentrate on being identical with each pass. Spray in straight lines, meaning draw imaginary lines in your head through the panel and follow them. Use a slow reducer. Omni reducer is garbage and you would be well served using a better one like SPI Slow. Reducer makes a huge difference in how well a base will spray and layout. Anyone who says different has no idea what they are talking about.
Main thing to remember is make you passes less wet with consistent overlap between passes.
 
To add to what Chris said, Omni base is not the easiest to spray in a color like that. The metallic will mottle easily and just stay like that. Personally, I have never had a drop coat fix a mottled base. It usually makes it worse, at least for me. Drop coats were for enamel where the light coat would melt in to the already wet substrate. I use that gun for clear all the time, but I have never sprayed base with it. It is designed to spray clear wet, not base, which Chris mentioned should be sprayed with medium coats. When adjusting the fluid, turn the knob all the way in, then turn out 2 turns. I turn the fluid knob out 2 1/2-3 turns for clear, which would be too much material for spraying base. Omni reducer is only good for cleaning your gun. SPI reducer would help a ton. I use slow year round.
 
Chris_Hamilton said:
You've got several issues from reading your post. First mottling in basecoats is a symptom of spraying too wet. Striping is a symptom of improper overlap. Improper overlap can result in mottling if you are double coating an area because you are inconsistent in your passes. Your issue is one or both of these things. In addition MR186 which is a medium reducer is really too fast of a reducer to use in all of but the coldest temps (60-65 degrees)
Also the Evo is a clear gun more than anything. It is not going to shoot silver metallic very well unless you throttle it down quite a bit. 3+ turns out is way too wet. When you spray base you only want to spray in at most medium coats. Try 1.5 - 2 turns out (max) and a 90%-100% full fan, to start with. Concentrate on 50-75% overlap each pass. Concentrate on being identical with each pass. Spray in straight lines, meaning draw imaginary lines in your head through the panel and follow them. Use a slow reducer. Omni reducer is garbage and you would be well served using a better one like SPI Slow. Reducer makes a huge difference in how well a base will spray and layout. Anyone who says different has no idea what they are talking about.
Main thing to remember is make you passes less wet with consistent overlap between passes.
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I'll try doing it earlier in the morning and turning in the fluid. I might have some spi reducer I could try. It didn't look wet really at all. All my other metallics have looked ok, this silver is just beating me up. I can only see the mottling at certain angles, so I definitely feel like the issue is the metallic. It's not visible from the top down or from the drivers side. What about ur50 for reducer?
 
texasking said:
To add to what Chris said, Omni base is not the easiest to spray in a color like that. The metallic will mottle easily and just stay like that. Personally, I have never had a drop coat fix a mottled base. It usually makes it worse, at least for me. Drop coats were for enamel where the light coat would melt in to the already wet substrate. I use that gun for clear all the time, but I have never sprayed base with it. It is designed to spray clear wet, not base, which Chris mentioned should be sprayed with medium coats. When adjusting the fluid, turn the knob all the way in, then turn out 2 turns. I turn the fluid knob out 2 1/2-3 turns for clear, which would be too much material for spraying base. Omni reducer is only good for cleaning your gun. SPI reducer would help a ton. I use slow year round.
Click to expand...
It has seemed like the drop coats just make it worse. They're just how I was taught to do it in school so I figured I should try. For clear I always just fully open the fluid, where it starts to hit the trigger. It's always come out like glass so far, I just move fast with it at that point.
 
You can also try using an intercoat or blending agent. SPI makes an intercoat which you can add to your RTS base to help even out the metallic. PPG makes DBC 500 which is similar to SPI's but much more expensive. Reduced Intercoat mixed 1:1 with your RTS base on the last one or two coats will help a lot if you are still having issues after doing what we said above.
 
I'll see about getting some spi slow reducer. Just means I have to wait a while. I see why PPG reducer would make sense, but why would spi reducer work better where ur50 wouldn't since they're both not in the same brand. Not doubting that spi reducer is good, I had some, it's all gone. Just curious with it.
 
texasking said:
It is not what is on the label, but what is in the can. The cheaper grade of reducers are full of cheaper solvents and moisture. SPI uses only the best raw ingredients, and the reducer is the best on the market. Always use slow, especially with a light metallic.
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Of course, but isn't ur50 also a quality reducer? It's always been touted as such and what was used at the schools and at shops still using solvent. Is there something wrong with it that I should avoid?
 
I have no experience with ur50. I am sure it is much better than Omni because it is their top of the line. It is also medium dry, which will cause problems in warm weather. Use slow unless you are spraying in very cool weather. The results will always be better. What is used at schools is what they can get for free, not necessarily the best products. Nothing against BASF, but if a different company came in with a better deal, they would suddenly become the best thing since sliced bread.
 
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Creativename said:
I'll see about getting some spi slow reducer. Just means I have to wait a while. I see why PPG reducer would make sense, but why would spi reducer work better where ur50 wouldn't since they're both not in the same brand. Not doubting that spi reducer is good, I had some, it's all gone. Just curious with it.
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The UR is too fast, and you want slow.
Ur is a good reducer, but you need slow and unsure what the UR reducer number is.
 
I'd imagine the reason the drop coats make it worse is because when you back away from the panel, the paint is already dry(wrong reducer) by time is hits the panel and the mettalics don't have a chance to settle.

I may be wrong, but thats what I have had happen to me in the hotter months.
 
So here's the final product. Using spi slow reducer and choking the gun down to 1.5-1.75 turns out. There's still one spot, but it's such a specific angle and I doubt people would notice without it being pointed out. I didn't see it before the clear went on. I figure at this point I'm just fighting the gun mostly. It kind of looks like a really light stripe, but only about a foot long and only a specific angle. I watched the gun angle and overlap closely, so I don't know if it's that or what.
 

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Nice job!
Here is something I had trouble with years ago, and you don't realize you are doing it on horizonal surfaces, which are the most common areas for stripes. It says he is going for 75% overlap, but it looks more like 90%

Sata 90 degree angle.jpeg


 
To more easily get the gun at a 90 degree angle on horizonal surfaces notice his fore finger is above the trigger, and the second and third fingers are on the trigger. This is just as important as fan adjustment.
Gun angle.jpeg
 
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