Automotive Paint

So...I bought a new truck. The manager throws me a pitch about how enviromentally friendly the new paint is that Bird droppings, tree sap, etc. will destroy it; if not for the clear coat. So I was wondering what kind of paint is this NEW paint? Is it more suitable to use on our planes now, because it doesn't have lead in it? Any ideas?

jon

Some research into the problem revealed that the clearcoat did not have an additive to stand up to UV, which would have cost about $1.50 per car to add. It seems Fords were meant to be kept out of the New Mexico sunshine!

That little experience and many others (as well as being "dollared" to death by the Taurus, including fuel pump, air conditioner, water pump, brake pad, steering gear, computer, CV joint, ignition module and transmission failures) ultimately caused me to write a "kiss off" letter to Fomoco, and end my "driven a Ford lately?" phase forever. (Even the volume pot in the radio failed!)

Now we own two big Chryslers, both with clearcoated paint, which is holding up well (one car was manufactured in 97) plus neither vehicle has ever left me walking in Dallas (or anywhere else)..

[photo not recovered: 3e69bb3870f12ad5.jpg]

"Experience is a good school but the fees are high." -Heinrich Heine

My son just got done painting a Fiero with PPG base coat/clear coat. Except for the problem of fumes from the clear coat, it is the way to go. The local PPG rep read him the riot act about keeping the stuff off you skin and out of your lungs. He dressed up in a full plastic suit, goggles, 3M chemical respirator, gloves, and a ton of vaseline on the little bit of bare skin. He still said he got dizzy spraying 2 oz. of the stuff on just the fender. But it sure do put on a nice shine and cover up blemishes in the basecoat!!

I'm planning to try the Nelson Paints water-based urethane clear with hardener. That is supposed to be a lot less of a problem. It can't be more expensive than the automotive finishes $90-150 a quart.

The base coat is pretty delicate. You can take it off with almost anything including rubbing alcohol if you run a little. Leaves a nice, matte finish that gives pretty good traction for inking. But it does take some touch to apply.

Randy Powell

edit: Gosh, 'zilla will go off on this.

AAAAARRRRRRRGGGGHHHHHHHHH!!!!!!!!!!!

Ignorance is bliss, isn't it?

<snipped from upcoming FM article by your truly>

Safety:

There are a lot of discussions about the potential safety hazards surrounding the catalyzed urethane paints, especially the auto clear coats. Years ago, when the Imron series of paints from Dupont were popular (a particularly hazardous paint system), there were several horror stories going around the control line stunt community. In following with these stories there were a lot of half-truths and misconceptions bantered about. Hopefully, some of that will be clarified here.

The first misconception is that any painting system is “safe”. There are simply no solvent-based painting systems that do not require proper protections. Without the proper breathing apparatus and protection from skin exposure all of the paints and glues used in modeling are unsafe to a certain degree (excepting the maybe aliphatic glues and their cousins). Dope systems are certainly not immune to safety concerns, as well as epoxies, enamels, and cyanocrates.

One of the main factors in evaluating whether a system is safe or unsafe is exposure time. This is one the most overlooked factors when comparing the hazard in each system. There are certainly addition chemical hazards when dealing with the clear stage of the auto paint systems, but the exposure times are so much drastically smaller in comparison to say, a dope system, that the case could be made that, in the end, the auto system is actually more safe. For example, for say a .60 sized stunt ship, a dope clear job would typically consist of one to two quarts of reduced material. This would typically require anywhere from 5 to 10 sprayed coats. If each coat requires 20 minutes of spraying time, the total exposure would be roughly from 2 to 4 hours. In comparison, for a .60 sized stunt ship, I typically spend about 10 minutes spraying the tack coat of auto clear and probably 10-15 minutes on the second wet coat (there is a lot more watching and looking on the final coat). Typically I only fill the spray gun with 6 to 18 oz of reduced material (depending the size of the airplane and the “high zootness” of the paint job). Due to this fact, it is easy to see that the total amount of atomized paint floating around in the air is drastically less with the auto clear.

As far as the safety of the total system outlined in this article, the exposure to any hazardous chemicals has been minimized. There is minimal exposure during the Polycrylic stages. I seldom feel the need to wear a mask and my wife never complains of the stink in the house, so the largest portion of the finishing process is spent with no stink at all. The primer stages are relatively quick, as only two coats are required, one rough and one final, and both of these could be accomplished in the same day if one is diligent. The basecoat colors are really quite benign, and have a smell similar to Red Devil Enamel. Since they gas off so quickly and use such mild solvents, skin exposure risks are also relatively mild. The clear is the most obvious health hazard, but the exposure is so short I feel the tradeoff is well worth it.

I just so happened to buy a new organic vapor mask, (a 3M silicone half faced model) so I took the opportunity to call the 3M Technical Service Line to get the 411 on the effectiveness of organic vapor “carbon masks” on diisocynates. Diisocyanates are the most hazardous chemicals present in the auto clears. Much to my surprise, despite what we have been told in the past, carbon based filter cartridges are completely affective against these chemicals, even more so than most solvents. The use of “fresh air systems” is not even advocated by OSHA under normal conditions. The only reason fresh air systems were EVER advocated for diisocynates was because there were no “warning signs” for these chemicals (like a smell). You can read the whole article here.

http://www.3m.com/occsafety/pdfs/respirator1.pdf

This is the “nuts and bolts” of the article.

Misconception No. 1: Air-purifying respirators should not be used because diisocyanates have poor warning properties.
Although OSHA specifically permits change schedules in lieu of sensory warning properties, some health and safety professionals argue this is not a safe practice. They believe diisocyanates could enter a facepiece through a spent cartridge or defect (e.g., a torn exhalation valve), and the user would be unaware, risking prolonged exposure.

Misconception No. 2: Air-purifying respirators cannot remove diisocyanates.
In fact, it has been known for many years that diisocyanates are adsorbed by activated carbon and retained extremely well. Cartridge breakthrough equations predict very long service lives for diisocyanates under plausible use conditions.

Misconception No. 3: Air-purifying respirators are not approved for gases and vapors with poor warning properties.
NIOSH supports OSHA’s requirement for change schedules and recommends against relying on warning properties. In addition, NIOSH recently directed respirator manufacturers to change the cautionary language on cartridge and canister approval labels and user instructions to be consistent with 1910.134. Specifically, the statement “do not wear for protection against organic vapors with poor warning properties or those which generate high heats of reaction with sorbent” must be changed to “follow established cartridge and canister change schedules or observe ESLI to ensure that cartridges and canisters are replaced before breakthrough occurs.”

Besides the inhaled vapors of any solvent or diisocyanate, there is also the risk of exposure to the skin. I personally take this very seriously, since the only adverse reaction I have had to the auto paints actually came from DIRECT LONG TERM EXPOSURE TO THE SKIN. I simply don’t recommend it. My latest method for avoiding skin exposure is wearing treated paper (Tyvek) hooded coveralls over my street clothes when I shoot the clear. I use the coveralls a few times and throw them in the trash. Then again I am lucky that I have a convenient supply in that my boss lets me have one every now and then. They are really inexpensive (there are several sources on the Internet and the price is about $50 a dozen) but still this may not be a good solution for everyone. Another alternative would be to go to the surplus store and get a set of Air Force mechanic’s light coveralls. This is what I did when I was in college. The coveralls lasted for years and cost me about $10. I still recommend showering after shooting an entire plane in clear; it just never hurts to be safe.

Done here.
GZ