New primer/alodine substitute-- anyone ?

[fairchild1934]

It is a product called "PreKote" by Pantheon.
It is being used by the air force and some airlines. Low toxicity compared to alodine.

Anyone have experience with this product ???

Tim B.

[alaskabearhawk]

That is all I used. It is great stuff, but follow the directions as it matters how it is applied. The test panel I made has been outside for two years now, always in the weather. In the direct Alaska summer sun, temps well below zero and everything in between. Ice, rain, snow, dirt, gravel…you name it. It’s been kicked around and still looks like new and paint shows zero signs of coming off. It is now owned by SOCOMORE.com

http://www.mykitlog.com/users/displa...ect=527&ca tegory=14107&log=300508&row=76

http://www.mykitlog.com/users/displa...ect=527&ca tegory=14107&log=300510&row=74

http://www.mykitlog.com/users/displa...ect=527&ca tegory=14107&log=300511&row=73

[SpruceForest]

Being a belt-and-suspenders + skin-staples-and-superglue sort of guy, alodine or primer alone are pretty much equivalent levels of protection, with the combination adding at least redundancy for thin spots, etc., and improved corrosion resistant over one or the other. Do we have similar data on PreKote? Given everyone seems to be out of alodine until April or so, I might have to look at options to keep my spar builds on track. Intent on retiring somewhere with lots of lakes and salt-water canals and very minimal/non-existent BOR violations, so my airplane is one of those that will just have to deal with the extra pounds of corrosion protection.

[Redneckmech]

I am using Pre-Kote and so far it seems to work well for primer adhesion. It has advantages and disadvantages in that it is non-toxic (I have small children that are into everything) but it requires priming within 24 hours of application which can be a tall order for a batch of wing ribs. Based on my research it seems to allow excellent adhesion for primer but provides no protection on its own.

[SpruceForest]

So in digging deeper, Pre-Kote looks like a viable substitute for the clean/etch part of aluminum prep, but as mentioned does not add any corrosion protection by itself.

To summarize:

Alodine is a two-step process that does two things: cleans and prepares the aluminum for further coatings (using something like IC-33/Alumiprep), and applies a chromate-based conversion coating (e.g., IC-1201/Alodine) to chemically passivate the surface. That protection comes from making the surface chemically inert, with the chromate conversion coating remaining somewhat mobile and able to protect against nicks, scuffs, and assembly-related surface damage (e.g., a rivet hole drilled after the coating is applied).

Adding a primer just improves the overall corrosion protection and resistance to surface damage, and the lit I can find indicates belt-and-suspenders protection with well-done Alodine and primer.

Pre-Kote provides the same or better cleaning and etch protection, but no additional corrosion protection, so it looks like a good first step in the Alodine process or prep for primer over bare aluminum.

One thing to note is the cost of the materials... Pre-Kote is a two-coat application process applied full strength at about $108/gallon, versus IC-33's single-coat brush/spray application at 3:1 dilution or 5:1 dilution, or dip application at 3:1 dilution, and about $65 per gallon undiluted. In summary, there appears to be a significantly higher cost (> 10x) associated with Pre-Kote versus IC-33 (but I admit I have not seen just how efficient Pre-Kote may be in brush application in terms of wasted material).

Other considerations:

- Full removal of IC-33 is needed for best paint adhesion and avoidance of contamination, so assembled surfaces will need a lot of water rinse to clean under rivets, lapped seams, etc.). Pre-Kote has less stringent rinse requirements, and appears to provide some evidence of better adhesion on existing built-up components (e.g., refinish work).

- Both Pre-Kote and IC-33 appear to require the usual splash and skin protection. Alodine and epoxy primer seem to be about equal in PPE, but commercial disposal of Alodine/IC-1201 can get very expensive. I suspect the military's allowed use of Pre-Kote had far more to do with this than any enhanced protection versus the mil spec Alodine/primer process.

For homebuilders away from salt water/maritime environments, not sure there is an advantage one way or another, beyond cost. For those in maritime environments, the additional corrosion protection over the lifespan of the airplane makes IC-33/IC-1201 an attractive option, as well as that lower total cost per sf for treatment.

[geraldmorrissey]

Spencer Aircraft, 253-848-9349, has quarts and gallons of Alodine 1201 in stock today. National aircraft 206-762-7278 also has quarts and gallons in stock today. They are not aware of any shortages.

[SpruceForest]

Thanks! Looking for a few more gallons.