Helpful Tip : FISH EYES OR WHATEVER

[customandsound]

Here i found this and i would like to pass it on the every one:
When there are problems in the paint finish, all direction is often lost on how to troubleshoot. Whether you have fish eyes (moon craters), hairs, lint, specks, or bumps, take your time. You must keep notes during any type of troubleshooting.
Start with coating test panels. These test panels must not be homemade from metal at your manufacturing location, but from an outside source which makes special test and sample panels. You can never eliminate the possibility the problem could be your metal! These test panels are now going to be exposed to each and every step in your finishing system, one step at a time. Remember, keep notes.

Start by coating your first panel at the spray booth. Write a number, letter, or a date, in the powder on the panel before it is cured in the oven. This type of a note is permanent and will eliminate panel mix-up. If the panel looks OK, then the problem is not in the spray booth, equipment, or powder.

Now back up another step in your finishing process. This could be the final rinse step in the washer. Dip a new test panel into the rinse tank of the washer, and dry it in your dry-off oven, coat it, mark it, and cure it. Now, how does it look? If OK then back up another step until the problem is found and corrected.

One final note, "Silicon" in a lubricant form and in a quantity as little as one part per million, will cause fish eyes (moon craters). It will not wash off in the washer but degreasing is better. It can come from a new wonder if being used in your air compressor. It also can come from the welding equipment where the nozzles are now being cleaned with a new anti-clog spray. The most amazing find of silicon was its use in sewing tread, as a lubricant. A small amount of this thread was then used to sew end splices to a filter belt used in a filter belt type spray booth. After two weeks of 80% rejects and 3,000 lb of wasted powder, the problem still remained. The filter belt was then replaced with a silicon-free belt. Fresh powder then solved the problem.

[jtagger19]

it would be nice if people post a problem they have had and how they solve it
and if posible a picture of the problem . cuz I have found that people often mix up names like fish eye and back ionization ,orange peel and pin holes ,ETC. and they try to solve the problems the wrong way.

[Zpider]

About the craters, my father used the same airhoses for the airtools in the shop a while back, and and we got craters in everything. I couldnt figure out why, but it turned out he sprayed silicone in the extensionhose instead of directly in the tool for lubricating it. So the tip is, use separate hoses for blasting/coating and other airtools, keep then free from any oil.

Also, when using a waterseparator on the system, place it as close to the tool as possible, most condensed water ends up in the hoses when the hot compressed air cools off in the hoses. So placing it on the compressor dont give any good result...

[LeeParsons]

Zpider, I'm glad you brouth that up. A long time ago in a place not so far away, I had a paint and body shop and we ran into the same problem. What I do now is use several water seperators close to the equipment that I need them on. I have on mounted on the side of my application booth with am 8' hose going from it to my gun. Another on the bench beside my blast cabint.

Another thing I do is, when I store air hoses I connect the two ends together. Helps keep the little crawlies and dirt out.

[PowderVisions]

Re: Helpful Tip : FISH EYES OR WHATEVER

Almost anytime you have crators or fisheyes it's because of something (soil)on the part or in the air. If you have more than one piece to paint, try using the water break free test first to insure you have an adequately clean part in which to apply the powder to. If you have already cured the part and it is showing these sign, you will probably need to strip the part using aircraft stripper.

The water break free test is as follows:

This is a test that tells you if you have removed all organic soils from the substrate.
Slowly pouring water onto a pretreated part and letting it flow over the entire surface performs the test.
You will visually watch the surface as this is being performed. If the part is water break free,
there should not be any areas that water beads around.
The entire surface should be continuous with no ?water breaking free?.

If there is water beading around or breaking around in a spotty fashion,
you still have organic soils on the surface and repeating the pretreatment process will be needed.
This is a good time to see if your substrate was overly soiled or if the wash system is in need of maintenance.
You should never apply a topcoat over a water break surface.
You will never get adhesion longevity without a ?water break free surface?.

A rule of thumb says the water-break test is reliable 90% of the time.
This test is especially useful on oily surfaces. Smut has no effect on a water break test.
Water will break freely over smut areas. Deposited hard-water salts cannot be detected with a water-break test.
A water-break test is also a measure of the cleanliness of the rinse water being used.
(Make sure your water-break test is being administered with clean fresh water).
A surface under test may, indeed, be clean, but the rinse water may be dirty.
Such dirty rinse water would bead up on a surface as if it were dirty.

[corybarta]

Re: Helpful Tip : FISH EYES OR WHATEVER

I always use a torch to ge the part stripped down, then blast it with my bead blaster then hang it. I use a stuff found at napa called prep clean. I spray that in there then use my torch and lightly heat it off. You can watch the moisture run out of the metal, then coat. Seams to work for me.

[uricad]

Re: Helpful Tip : FISH EYES OR WHATEVER

I always use a torch to ge the part stripped down, then blast it with my bead blaster then hang it. I use a stuff found at napa called prep clean. I spray that in there then use my torch and lightly heat it off. You can watch the moisture run out of the metal, then coat. Seams to work for me.

...a torch huh?.... interesting... Sounds like lots of toxic fumes-nothing exhaust fans can't handle, right? Does it work good? How long does it take?...say for a square foot. What types of coatings does it work on?

[uricad]

Re: Helpful Tip : FISH EYES OR WHATEVER

...a torch huh?.... interesting... Sounds like lots of toxic fumes-nothing exhaust fans can't handle, right? Does it work good? How long does it take?...say for a square foot. What types of coatings does it work on?

Oh Yeah...What about warping?

[JTW37]

Re: Helpful Tip : FISH EYES OR WHATEVER

The whole idea to the torch thing is to just pass it over your part to clear it of dust bunnies and rag ravel. Don't heat the part up anymore then just passing over it. I use this method all the time. No more bunnies.

[nuttyman]

Re: Helpful Tip : FISH EYES OR WHATEVER

he was referring to a rose-bud torch to burn off the powder. it works well, just be careful & do not use this method on Al.

[stevedwnng]

Re: Helpful Tip : FISH EYES OR WHATEVER

I noticed some dirt specs on the finish of a valve cover I did. I disassembled and inspected everything and couldn't find the cause. I'm always careful about keeping my gun clean, probably to the point of overboard. I took the air fitting off my air hose and ran a q tip down into the hose and it came out dark brown. I went out and bought a brand new air hose, a new water separator, moisture separators, and some in line desiccant air dryers. I also cleaned all the fittings and couplers out. I also went one step more and tried again using another compressor. Instead of using my old 220v monster that has some worn rings (oil blowby) I used my dads little 1/2 hp oil less compressor. The following pics are the results. Fisheye everywhere. I didn't spray any silicone anywhere, baked the part at 450 for over an hour, thoroughly blasted the part, wiped it down with acetone until dirt would no longer appear on the rags, and did the water break test, ect. The rags are brand new micro-fiber towels that I cut into pieces and there are no chemicals in the towels. I've used them before with no problems. I applied iron phosphate and rinsed thoroughly before putting the part back in the oven to bake off any residual moisture before applying powder. I can't for the life of me figure out what is causing the fisheye. Here are some pics. Any ideas guys? I hope it's just something I'm overlooking.

[Harleydad]

Re: Helpful Tip : FISH EYES OR WHATEVER

Still surface contamination of some sort. It seems as though you have taken steps to eliminate the air supply. Have you cleaned your oven lately? After the outgassing who knows what floats around in there.

[stevedwnng]

Re: Helpful Tip : FISH EYES OR WHATEVER

I clean the oven with a tack rag to pickup the dust and stuff that collects on the top of the oven above the burner elements. I think that when i was using the old air line, it blew oil into the powder in the cup. When I put the left over powder back in the bottle it contaminated the rest of the powder.

[Harleydad]

Re: Helpful Tip : FISH EYES OR WHATEVER

I clean the oven with a tack rag to pickup the dust and stuff that collects on the top of the oven above the burner elements. I think that when i was using the old air line, it blew oil into the powder in the cup. When I put the left over powder back in the bottle it contaminated the rest of the powder.

Entirely possible

[stevedwnng]

Re: Helpful Tip : FISH EYES OR WHATEVER

Well the good part of it is, I used the last of that powder when I did that. The color partial cured with no problems, but the fisheye appeared when the clear started curing. I used the last of both of them on that piece so I just ordered new powder. I'm going to do another test piece with another powder and see what happens. Is there a fisheye eliminator additive?