STUG GROWING HAIR & MY AUFKLARUNGSPANZER

My first guess would be that you didn't allow enough cure time between layers. Each layer needs able time to outgas and fully cure. Adding another layer makes that process longer and in some circumstances mixing products will cause a reaction between the two...which is why the hair grew.

How did you apply the paints? Brush or airbrush? 

I think Jerry has it, but 24 hours should be enough between coats, unless the coats are very heavy.

Can you post a picture or two? 

Thanks Ross, I've been searching. Found it, thanks

Congratulations, you are the proud owner of a moldy tank.  Sounds like the inability of the model to dry.  How's the humidity where you are?  A couple ideas.  Put the model in the sunshine or in a dry, warm area, and see if the growth subsides or stops.  Even when the mold disappears, there may be a residual spot left over.  Clean gently with a Q-tip and some MILD soap and warm water.  Hopefully you won't pull paint.  Good luck.

Had the same thing happen to me when I used Celluclay for a tank base.  I had mold everywhere.  Put it in the sun for a day, and the only place it remained was under the tank where the sun didn't shine.  It finally went away when it dried completely.

Gip Winecoff

You need to put the following on the ends of the link, replacing the { and } with square brackets [ and ]: {img}your picture link{/img}

Or, click on the image icon in the message toolbar (next to the smilies button) and fill in the blanks on the form that pops up. 

That looks like dust to me, specifically cloth or paper fibers. If these are on the surface (or fall on it while the paint is still wet), they will rise up and curl like that when you apply a coat of paint—and its worse for flat clear coats.

Try raising the relative humidity to at least 50% at least half an hour before spraying. Run the spraybooth for half an hour before spraying, too. Misting the air in the room with a spray bottle can also help. A room air filter works too.

Finally, something I'm going to try soon is a breeze box fan with a furnace filter taped to it.

Well, mold it ain't.  Sorry, I was wrong.  What it looks like is stringy spray from your airbrush, almost like a miniature Silly String.  Are you diluting your flat coat appropriately, and mixing the flat coat thoroughly prior to spraying?  In addition, how old is the flat coat, and have you previously mixed other solvents into the "virgin" product?

If all else fails, a Gillette Mach 3 should do the trick.  But be prepared; according to the commercials, girls are really drawn to it. 

Gip

Thanks for the responses, Ross the paint booth is clean, humidity factor should be high enough in the secure basement room. Gip, It does look like miniature silly string. The Testors dullcoat is fresh since the Stug has been painted.What % mixture would you recomend, I have a good friend that says just enough to get it through the airbrush & his pieces turn out pristine. He did suggest not knowing for sure or not if there might be a static charge from the paint booth. Could that be a possibility and if so why only when using the dullcoat?

                                                                     Charlie

doc-hm3 wrote:

... Thanks to Bgrigg and his sticky, even I can post pic's.

You're very welcome. I made it so that everyone could post pics!
I only wish they did make it a sticky. I keep having to bump it up to the top of the thread. 

Your booth looks great.  What kind of cfm is your fan pulling?

In answer to your previous question, I normally use a spray (rattle) can, but in the past I would thin my flat about 50/50 or so.  Any thicker, and I would wind up with white spots from spraying too much/too close--but no "hair".

OK, this is a wild idea, and anyone reading this will probably consider this totally stupid, but since flat coat is a lacquer, and lacquers are, by definition, typically resinous, curing is actually the process by which they "dry".  The warmer it is, the faster resins will cure.  Looking at your hood lights, it would appear that a bulb utilized with a metal fixture like the ones you're using could generate some significant heat through simple reflectance.  Just wondering, but if because your mixture is such that you're "just getting it through the brush" coupled with the heat of the lights and variances in spraying distances, could the flat be curing as it leaves the airbrush AND hits the model (The model would be warmer because of the lighting.)?  In addition, if there is any dirt, residual paint, or a burred needle in your airbrush, you could be getting an uneven flow through the tip, causing an uneven aerosolization(?), that is, it ejects from the brush thicker in one area than in another.

OK, it's getting late, and I'm really tired.  If the above doesn't make any sense, see the previous statement.  Just some weird ideas to try to help out...

Happy Easter

Gip

Dust is funny stuff—and I still think it's airborne fiber.

Admittedly, your work area looks pristine—but the only way the human eye can see dust is as "motes" in a strong beam of light.

Static, especially in dry conditions, is a real bugaboo. It will make even the tiniest amout of airborne particulate stick to a surface.

There are two sources of static charge apparent in your setup: the fan in the spraybooth, and the stream of aerosolized, reduced paint coming from your air brush. 

In the winter, it is not unusual to have relative humidity below 40%, even in the basement—which is also where the biggest fan in the house is located, in your furnace.

I note that the "hair" tends to be concentratied in specific areas—generally indicative of differential static charge.

Flat coats contain microsilica, which has very peculiar properties when it comes to static charge. Any place you have a small fiber on the surface, a flat coat will make it stand up in dry conditions.

Increasing the reduction (thinning) will help, as evaporating solvent will tend to carry off surface charges before they cause a problem.

I have to admit: anything that causes both Gip and I to scratch our heads in puzzlement definitely is classified as "weird."

I have had that happen to me a few times over the years using lacquers. The automotive primer I use will do it if I don't thin it enough and the pressure is to high. Sometimes it will trick you and work ok on a flat even surface but create spider webs like yours in recesses or nooks and crannys. The clear coats will turn white sometimes too.

Thinned 50/50 sounds good to me and crank down the air pressure. (I'm not saying to try this on your beautiful model, maybe on a test bed, but sometimes I'll add a few drops of mineral spirts to the mix to slow down the drying and get the coat to go on kind of wet. It works for me at least?)  HTH

 Dr. I think you may have found the culprit, I forgot to add TURPENOID!!! to slow the drying time. I generally shoot @ 12-15#'s pressure. I'm going to try the tupenoid theen I'll get back to you guys, THANKS!!!

                                                                                     Charlie

The only time I've ever seen anything remotely like this was when I used flourescent Testors but not on the model, just stringy residue at the ab tip.

What are you using for thinner? I've always used regular old hardware strore $2 a gallon paint thinner.

You nementioned two 3/4 color cups of clear? That sounds like a wholel of of paint to me. You should have more than enough in a half color cup to get a good cover on a 1/35 StuG.

You mentioned toilet paper to clean. tthat stuff is made to break down rapidly. Try old t-shirts, pipe cleaners, Q-tips or cotton balls instead, even paper towels.

Okay, I've reviewed the whole thread, looked carefully at the pictures, again, and cogitated (that  word's derived from grinding the cogs of the brain) on it, and here's what I think may be occuring:

A combination of too rapid drying (not enough reducer, too volatile a reducer), static charge (developed partially from the airbrush flow, dry air, and evaporation) a little dust or fiber (see ajlafleche's post—Swiffer cloths are good for wiping down a model before you paint, they don't leave even microscopic lint) that acts as nucleation sites, and a flat coat containing microsilica, resulting in:

the cotton candy effect. Ever see them make cotton candy? It looks just like this and is made by almost the same process.

All the remedies have already been mentioned: low airbrush pressure, higher humidity, less volatile solvent or cosolvent, and something to remove surface dust on the model before painting. As to the last, the flecks of dust are microscopic, but they serve as "seeds" for the strings to form.

Let us know what happens. This has been interesting. I hope it becomes uninteresting soon! 

Triarius, I have been using a Badger Crescendo with the medium tip/nose and checked the needle tip to cone tip and the needle is not bent but is off center.

                                                                   Charlie

I assume you are addressing the turbulence issue? Even if the needle were perfectly centered, any jet of air/particles will create some amount of turbulent flow. An aerosol cannot avoid it because of the different and constantly changing density of the flow cone. Some air brushes are engineered to reduce turbulence, but they only reduce it. Once that flow encounters the shapes, angles, and cavities of your model, turbulence goes  up tremendously—right where it will do the most harm. The only thing that can be done to reduce it at that point is to reduce the flow velocity—air pressure.

I'm not familiar with your airbrush. Is it gravity fed or siphon? Siphons need more pressure, gravity fed brushes much less (as I found to my chagrin when I switched from my old, reliable Paasche H to a T&C Omni 4000 ). The model looked like I had flocked it! Thank the gods of chemistry for Windex…

My point (theory ) is that your "hair" is the result of a combination of factors, most of which are readily addressed.  

And I'll bet you a dark, chewy beer that the relative humidity in your basement is much lower than you think it is. Here in the soggy midwest, when the humidity goes down to 50% in the mugid days of summer, we feel like it's pleasantly dry. In the winter, indoors, when we raise the humidity to 50%, it feels like a swamp. (And I have all too much experience with swamps!  )

  Gip, Sorry about how long it took to reply. The motor is a Dayton, 1TDT2, 1/10thhp @ 549cfm. I have a three stage filter in place, so I don't really know what she's pulling, but she's pulling well.

  Triarius, The Crescendo is the Badger #175, she came with 3 tips and needles small, medium & large. She is a bottom/siphon feed unit. I generally shoot at around 12-15#'s of pressure and the basement is finished and a constant 67-68 degrees.