Prekote as an alternative for Alodine

I am using Prekote instead of Alodine on my RV-8. See http://www.toadsrv8.com/Log/20071008.aspx for a discussion of my use of Prekote in preparation for priming.

The MSDS can be found at http://www.pantheonchemical.com/documents/PreKote%20MSDS.pdf. There are two chemicals listed as active ingredients (Diethylene Glycol Monobutyl Ether (DGBE) and N-Methyl-2-Pyrrolidone (NMP)), but I'm not sure what role each plays.

What I do know is that Prekote is not intended to serve as a corrosion preventer. It serves only as a surface prep to increase primer adhesion. In that role it does very well. I have had excellent primer adhesion using two-part chromated epoxy primer. Since my primer is chromated, I am relying on that layer as corrosion protection.

I figure if it's good enough for the US Air Force, it's good enough for me.

Cheers,
Nate Garrett

P.S. - No relation to the company in question - only a satisfied customer.
 
I figure if it's good enough for the US Air Force, it's good enough for me.


I think you better ask the guys using it in the airforce and not prekote. The airforce is not getting good results
 
HEGASIS said:
I figure if it's good enough for the US Air Force, it's good enough for me.


I think you better ask the guys using it in the airforce and not prekote. The airforce is not getting good results
Click to expand...

Richard,
I'm with Mark here. This thread has popped up several times in the past. Several years ago this question was asked on the Matronics RV list. I contacted fellow RV-8A builder Jerry Esquenazi about it. At the time, Jerry was a flight instructer at Randolf Airforce Base. He checked with the crew chiefs. They HATE the stuff. They only use it because the EPA is forcing the military to try and fine more environmentally friendly chemicals.
Prekote is hyping the Airforce use of the product. That doesn't mean that the Airforce thinks it's as good as chromate conversion products like Alodine or Iridite.
The crew chiefs reported that:
Prekote requires MORE not less prep work.
Primer adhesion with Prekote is not as good as with chromates (ie Alodine & Iridite)
Prekote offers NO corrosion protection.
They had several aircraft which exhibited peeling paint after several months using Prekote. I should note that this may simply be, because the techs were unfamiliar with the product at the time.
Bear this in mind. All the scarely language in the various MSDS's is based on you being exposed to the stuff 40 hours a week for multiple years. By using latex gloves and a modecum of care, you can Alodine every part on your airframe without getting the stuff on you.
Charlie Kuss
PS If you desire, I can look to see if I have Jerry's original reply regarding Prekote.
 
Charley,

I live in a rural area and have a well and septic system, so I am trying to keep any nasty stuff out of the water supply; thus my interest in Prekote or other products safer than Alodine. In doing further research yesterday, however, I found that chromates attach to soil particles and are not mobile in the soil, so the stuff is probably not a problem for water supplies. The health problem seems to be primarily from inhaling chromates. This was a question I asked earlier and was not able to find an answer to.

Regarding how well it works, I will check with my buddies at the Air Guard where I used to work & report back. I can imagine that the dissatisfaction may come from not applying it correctly--learning curve & all that. Of course, if it is difficult to use correctly, I could have the same problem.

Richard Scott
RV-9A Fuselage
 
Prekote used for internal vs external priming

Gents,

I have seen the post you speak of. It is my understanding that the message regarded external priming of complete aircraft.

I am using Prekote only as a prep for internal components. I can tell you that I have had excellent primer adhesion. I routinely have had the bucking bar hit the primered parts during riveting and it barely mars the primer.

As for prep time, I have never alodined so I can't speak to the time involved there.

If I have a big batch of parts, I will lay them all out and then clean them with a soapy scotchbrite pad first. Then the Prekote process (found at http://www.pantheonchemical.com/documents/PreKote%20Aircraft%20Application%20Procedures.pdf) is: spray prekote and scrub with scotchbrite - let dwell for two minutes (I do a number of pieces at once). Apply prekote a second time and scrub, and then rinse. It took me approximately 15 minutes to Prekote all of the parts for the Vertical Stabilizer.

Again, the major difference between Alodine and Prekote is one is a corrosion preventer while the other is not. I think that Prekote does just fine as a method of prepping aluminum for priming (as one of many effective methods). I chose it because it's easy to use, does not require hazmat shipping, and requires no protective equipment beyond a pair of rubber gloves.

Mi dos centavos,

Nate
 
Nate
Thanks for your clarifying post. Glad to hear that this stuff does work regarding primer adhesion. I suspected that the crews at Randolph had "learning curve" problems.
Have you ever used chromate conversion products? For our uses, there would be no inhalation problems, if used in a shop or garage with the overhead door open. These products are 98% water. They are a very dilute chromic acid solution with a gold dye and other products added. Short of spilling the stuff on yourself, there is no danger.
For disposal, I leave my 5 gallon storage buckets out in the sun to allow the water to evaporate. After several weeks, what remains is reduced to a "sludge" which I take to my county hazardous waste disposal site for proper disposal.
Richard,
Don't worry to much about "health" issues using the chromate products. Just use some care and common sense. Most of the health issue stuff is grossly overblown by folks who have never used the products.
If you spill some on you, flush the area immediately with water. The dye in these products will turn your skin yellow for a few days if not rinsed off immediately. [Ask me how I know :-( ]
Use whichever product you want. If you use Alodine or Iridite, do NOT place your soaking tank of Alodine in direct sun light. These products are photo chemically reactive. The sun light will ruin the product. For this reason, store your left over product in sealed containers in a dark area. I use 5 gallon paint buckets for storage. I keep these buckets under my work bench at the rear of my shop (away from the door & sun light).
If interested, contact me off forum for detailed info on using Alodine/Iridite products.
Charlie Kuss
 
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