I remember reading about PreKote a while back and wondered if anyone had any experience with this. Since I am getting ready to send in my empennage order, I was hoping to find a easier to use, less toxic alternative to Alodine. Is this stuff good for using on all the internal parts that normally get alodined? Or is it only good for using as a primer for painted surfaces?
Van's Air Force
Don't miss anything! Register now for full access to the definitive RV support community.
PreKote
- Thread starter zsadecki
- Start date
Hi,
I don't use PreKote yet, but have done a lot of research on it. If you haven't already, Google on 'PreKote' and you'll find a lot of info.
Like alodine, PreKote is an adhesion promoter - it helps primer or other coating adhere better to a substrate (i.e., your airplane). Unlike alodine, it doesn't provide any corrosion protection on its own. So if you intend to use a corrsion-inhibiting primer, PreKote might be worth considering. If you were just planning on alodine alone for corrosion protection, PreKote won't help.
Hope this helps...
Dave
I don't use PreKote yet, but have done a lot of research on it. If you haven't already, Google on 'PreKote' and you'll find a lot of info.
Like alodine, PreKote is an adhesion promoter - it helps primer or other coating adhere better to a substrate (i.e., your airplane). Unlike alodine, it doesn't provide any corrosion protection on its own. So if you intend to use a corrsion-inhibiting primer, PreKote might be worth considering. If you were just planning on alodine alone for corrosion protection, PreKote won't help.
Hope this helps...
Dave
Davepar
Well Known Member
Another less-toxic alternative is Aircraft Finishing Systems one-part water-borne epoxy primer-sealer, http://www.aircraftfinishing.com. It's not as resistant to scratching as alodine or two-part epoxy primers, but it's certainly less toxic. I've had pretty good success with it, although lately I've been getting lazy and just hitting stuff with Sherwin-Williams GBP-988 in a rattle can.
Dave
Dave
disturbing comment
After seeing this on the matronics list (originally from the old yahoo RV8list), I am beginning to rethink my decision to PreKote... I haven't started anything yet, so I still have time
I am joining the RV8 group on yahoo to post a question to Mr. Esquenazi, and see if there is any new info...
> From: "Jerry Esquenazi"
> <<http://groups.yahoo.com/group/rv8list/post?postID=yqSbOY-XljiOfaus-BJOYTNhkRbLUEy3aQP5DVbtL3MPCBpEVoULIcbk9YQCbGEO09rjgWQ>jlintx@g...>
>
> Date: Sun Jan 25, 2004 10:14 am
> Subject: Prekote update
>
> I spoke with the chief of the corrosion shop here on base. When I asked
> him about Prekote, he chuckled. Not a good sign. This man is very familiar
> with Prekote. He has been directly involved with it's use and has given
> briefings concerning it's use and performance. In a nutshell, he said the
> he would give his right arm if he could get rid of Prekote and go back to
> etch/Alodine! He said they have had paint peeling within 4 months of
> application. This surprised me... He said the application of Prekote is
> actually more labor intensive because Prekote is applied in 3 steps v.s.
> the 2 steps of the etch/alodine.
> This is something the previous articles said was an improvement over the
> Alodine process. He also said the Prekote application manual requires
> special water (distilled or de-ionized or something like
> that)for the rinsing process. It sounds like the articles were a bunch of
> propaganda. It's use in the AF is being mandated in the tech orders. I'm
> going to call some of the other bases to see if
> they had similar results. BTW, he invited me to come over to the shop the
> next they prep a T-38 so I can see the process myself. I'll keep you guys
> posted.
> Jerry
After seeing this on the matronics list (originally from the old yahoo RV8list), I am beginning to rethink my decision to PreKote... I haven't started anything yet, so I still have time
I am joining the RV8 group on yahoo to post a question to Mr. Esquenazi, and see if there is any new info...
> From: "Jerry Esquenazi"
> <<http://groups.yahoo.com/group/rv8list/post?postID=yqSbOY-XljiOfaus-BJOYTNhkRbLUEy3aQP5DVbtL3MPCBpEVoULIcbk9YQCbGEO09rjgWQ>jlintx@g...>
>
> Date: Sun Jan 25, 2004 10:14 am
> Subject: Prekote update
>
> I spoke with the chief of the corrosion shop here on base. When I asked
> him about Prekote, he chuckled. Not a good sign. This man is very familiar
> with Prekote. He has been directly involved with it's use and has given
> briefings concerning it's use and performance. In a nutshell, he said the
> he would give his right arm if he could get rid of Prekote and go back to
> etch/Alodine! He said they have had paint peeling within 4 months of
> application. This surprised me... He said the application of Prekote is
> actually more labor intensive because Prekote is applied in 3 steps v.s.
> the 2 steps of the etch/alodine.
> This is something the previous articles said was an improvement over the
> Alodine process. He also said the Prekote application manual requires
> special water (distilled or de-ionized or something like
> that)for the rinsing process. It sounds like the articles were a bunch of
> propaganda. It's use in the AF is being mandated in the tech orders. I'm
> going to call some of the other bases to see if
> they had similar results. BTW, he invited me to come over to the shop the
> next they prep a T-38 so I can see the process myself. I'll keep you guys
> posted.
> Jerry
Highflight
Well Known Member
I'm not going to comment on the merits (or not) of PreKote, but there are a couple of things I think need exploring.
In the comments made by the disappointed user, he said two things that caught my eye.
One is that "He said they have had paint peeling within 4 months of application". That's quite a stretch to assign the cause directly to PreKote itself. There are SO many things that can be done wrong in the application process that I wouldn't take a single anecdotal comment like this and assume that the PreKote was the problem. If it were, then EVERY use of PreKote would be reported as problematic, and that's not the case as far as I know.
Of course, when something goes wrong, it's always handy to blame something else other than our own carelessness for the problem.
If this same painter has problems with PreKote over and over, but others don't, well; like I said...
There may very well be other unintentional problems that are being introduced into their paint system that they haven't figured out yet. (I mention elsewhere how a guy spraying ArmorAll 50 feet or more away from a paint area can literally destroy a paint job. So what other "stuff" might these people have around that might be causing problems?...)
It's also important to know exactly WHERE the peeling is taking place.. does it peel to bare metal?.. between the PreKote and the primer?... between the primer and the paint?... just around corners and sharp edges?.. or on leading edge surfaces?
Once you know the exact layer and location where delamination (that's pro-talk for "peeling" ) is happening, then you are just BEGINNING to investigate the cause of the problem.
Then here's some more questions to ask:
1. Were the color coats "pushed" where one was applied on top of the next before proper flash time? Or did they wait too long between coats of ANY of the sprayed liquids?
Pushing sprayed coats (of primer or paint) can trap solvents, and that is a common cause of paint failure in "production" paint facilities where time IS money.
Waiting too long between coats can prevent proper "involvement" between the coats that you need, but more likely, it CAN allow contaminants to settle into the paint between coats.
2. Were any non-approved thinners used at ANY time in ANY of the sprayed substrates? Some painters think that "thinner is thinner" and dump anything they find on the bench into their paint cup if they need to cut viscosity.
3. Were the correct hardners and reducers used that were recommended by the manufacturer for the temperature that day?
4. In production shops, short shelf-life chemicals get used up pretty fast so this is not usually a problem, BUT, could the hardner used in the paint have been past it's shelf-life?
And that's only the beginning of investigating causes of paint failure. The list can get quite long, and yes, the list will include how the PreKote was used as well.
Also, he says: "He also said the Prekote application manual requires
special water (distilled or de-ionized or something like
that)for the rinsing process. It sounds like the articles were a bunch of
propaganda. It's use in the AF is being mandated in the tech orders.
The manufacturer is covering two bases here. First, using DI or RO water is a VERY good idea for rinsing because it is "possible" that minerals in local hard water can create big-time problems. This doesn't go for just PreKote, but this also applies to ALL other conversion systems as well. He should have been taking the same precaution (or more appropriately, at least knowing about the possibility of MAYBE needing DI or RO water for rinsing) when he used to use Alodine.
The second base that the manufacturer is covering is that, by making that statement, they are making it clear that they will not be responsible for the improper use of their product, and rinsing their product with water that could CAUSE a problem would be improper use of their product.
For the most part, we won't normally come across problems with hard water, but it CAN happen so if you think you live where the mineral content of your water is high, then you'll want to avoid using it for rinsing.
I just had to say something here because I have years of experience dealing with painters who made blaming anyone else but themselves (for their problems) into a fine art.
Free Hint: When in doubt, read the P-Sheet... and BELIEVE IT!
Vern
RV7-A
In the comments made by the disappointed user, he said two things that caught my eye.
One is that "He said they have had paint peeling within 4 months of application". That's quite a stretch to assign the cause directly to PreKote itself. There are SO many things that can be done wrong in the application process that I wouldn't take a single anecdotal comment like this and assume that the PreKote was the problem. If it were, then EVERY use of PreKote would be reported as problematic, and that's not the case as far as I know.
Of course, when something goes wrong, it's always handy to blame something else other than our own carelessness for the problem.
If this same painter has problems with PreKote over and over, but others don't, well; like I said...
There may very well be other unintentional problems that are being introduced into their paint system that they haven't figured out yet. (I mention elsewhere how a guy spraying ArmorAll 50 feet or more away from a paint area can literally destroy a paint job. So what other "stuff" might these people have around that might be causing problems?...)
It's also important to know exactly WHERE the peeling is taking place.. does it peel to bare metal?.. between the PreKote and the primer?... between the primer and the paint?... just around corners and sharp edges?.. or on leading edge surfaces?
Once you know the exact layer and location where delamination (that's pro-talk for "peeling"
) is happening, then you are just BEGINNING to investigate the cause of the problem.Then here's some more questions to ask:
1. Were the color coats "pushed" where one was applied on top of the next before proper flash time? Or did they wait too long between coats of ANY of the sprayed liquids?
Pushing sprayed coats (of primer or paint) can trap solvents, and that is a common cause of paint failure in "production" paint facilities where time IS money.
Waiting too long between coats can prevent proper "involvement" between the coats that you need, but more likely, it CAN allow contaminants to settle into the paint between coats.
2. Were any non-approved thinners used at ANY time in ANY of the sprayed substrates? Some painters think that "thinner is thinner" and dump anything they find on the bench into their paint cup if they need to cut viscosity.
3. Were the correct hardners and reducers used that were recommended by the manufacturer for the temperature that day?
4. In production shops, short shelf-life chemicals get used up pretty fast so this is not usually a problem, BUT, could the hardner used in the paint have been past it's shelf-life?
And that's only the beginning of investigating causes of paint failure. The list can get quite long, and yes, the list will include how the PreKote was used as well.
Also, he says: "He also said the Prekote application manual requires
special water (distilled or de-ionized or something like
that)for the rinsing process. It sounds like the articles were a bunch of
propaganda. It's use in the AF is being mandated in the tech orders.
The manufacturer is covering two bases here. First, using DI or RO water is a VERY good idea for rinsing because it is "possible" that minerals in local hard water can create big-time problems. This doesn't go for just PreKote, but this also applies to ALL other conversion systems as well. He should have been taking the same precaution (or more appropriately, at least knowing about the possibility of MAYBE needing DI or RO water for rinsing) when he used to use Alodine.
The second base that the manufacturer is covering is that, by making that statement, they are making it clear that they will not be responsible for the improper use of their product, and rinsing their product with water that could CAUSE a problem would be improper use of their product.
For the most part, we won't normally come across problems with hard water, but it CAN happen so if you think you live where the mineral content of your water is high, then you'll want to avoid using it for rinsing.
I just had to say something here because I have years of experience dealing with painters who made blaming anyone else but themselves (for their problems) into a fine art.
Free Hint: When in doubt, read the P-Sheet... and BELIEVE IT!
Vern
RV7-A
Last edited:
Vern,
The quote from the old RV8 Yahoo groups was not from an RV builder. It was a quote of an experienced US Airforce crew chief on the experiences of all the maintenance crews at Randolf Air Base. RV8 builder Jerry E. was a flight instructor there.
I think that the experience of professionals should be heeded. The ONLY reason that Prekote was been used (in limited testing) by the US military, is because disposal of very large amounts of chromate wastes are expensive and frowned upon by the EPA. The military is looking for a more environmentally friendly replacement for chromates (Alodine, Iridite, etc)
To give a little back ground on the original thread from the old Yahoo RV8 group, someone asked about using this product. Another lister commented that it must be good, because Prekote was touting that the military was using it. No first hand info was offered either for or against it's use.
I asked Major Esquenazi (Jerry) to ask the crew chiefs at Randolf (where he was stationed at the time) what their opinion of Prekote was. The quote regarding problems with it's use came from said crew chiefs, through Major Esquenazi's report to the old Yahoo RV8 list. I think anyone considering using this stuff needs to ask themselves the following.
If trained military personnel had poor results, can I (you) as a first time user have better results with it? I'd suggest sticking to a chromate or perhaps the SanChem product mentioned by another lister.
Charlie Kuss
The quote from the old RV8 Yahoo groups was not from an RV builder. It was a quote of an experienced US Airforce crew chief on the experiences of all the maintenance crews at Randolf Air Base. RV8 builder Jerry E. was a flight instructor there.
I think that the experience of professionals should be heeded. The ONLY reason that Prekote was been used (in limited testing) by the US military, is because disposal of very large amounts of chromate wastes are expensive and frowned upon by the EPA. The military is looking for a more environmentally friendly replacement for chromates (Alodine, Iridite, etc)
To give a little back ground on the original thread from the old Yahoo RV8 group, someone asked about using this product. Another lister commented that it must be good, because Prekote was touting that the military was using it. No first hand info was offered either for or against it's use.
I asked Major Esquenazi (Jerry) to ask the crew chiefs at Randolf (where he was stationed at the time) what their opinion of Prekote was. The quote regarding problems with it's use came from said crew chiefs, through Major Esquenazi's report to the old Yahoo RV8 list. I think anyone considering using this stuff needs to ask themselves the following.
If trained military personnel had poor results, can I (you) as a first time user have better results with it? I'd suggest sticking to a chromate or perhaps the SanChem product mentioned by another lister.
Charlie Kuss
Highflight
Well Known Member
Charlie, I'm going to repeat myself and say that if Prekote was problematic, then EVERY application and use of it would be problematic.
When you get a general consensus from everyone (professionals only, please) you talk to, then I'd have to agree that Prekote is the problem.
After having said all that, I don't know why anyone would consider using it anyway. It's main stated purpose is to promote adhesion but with no corrosion protection.
What that means to me is that if you want a simple system, then use something that's been proven time and again to work incredibly well like an epoxy primer (e.g., PPG DP-40).
While DP-40 is not specifically designed for corrosion protection, when applied over just clean aluminum, it WILL serve as a very good long-term corrosive protective barrier.
Personally, I'm going with Sanchem in the tail because it adds no extra weight being that's it's not a "coating", but I will be spraying all the inside edges of joining panels so that there is an epoxy barrier between the panels.
I believe in "wet" riveting, although you can wait a few hours for the DP-40 to tack dry before riveting (to avoid the big mess) and still get the benefit of wet riveting.
When you get a general consensus from everyone (professionals only, please) you talk to, then I'd have to agree that Prekote is the problem.
After having said all that, I don't know why anyone would consider using it anyway. It's main stated purpose is to promote adhesion but with no corrosion protection.
What that means to me is that if you want a simple system, then use something that's been proven time and again to work incredibly well like an epoxy primer (e.g., PPG DP-40).
While DP-40 is not specifically designed for corrosion protection, when applied over just clean aluminum, it WILL serve as a very good long-term corrosive protective barrier.
Personally, I'm going with Sanchem in the tail because it adds no extra weight being that's it's not a "coating", but I will be spraying all the inside edges of joining panels so that there is an epoxy barrier between the panels.
I believe in "wet" riveting, although you can wait a few hours for the DP-40 to tack dry before riveting (to avoid the big mess) and still get the benefit of wet riveting.
Prekote
I used prekote because I found it very hard to get alodine here in Switzerland, even though
one of my neighbors is the sales rep for Henkel (alodine manufacturer) in this area. He could get me
the touch-up pens, and that's all. For some reason, these Swiss guys don't want chromates in their
water. I don't get it!
I didn't follow the directions to the letter. I used tap water to rinse off the parts, and I didn't paint
them for about 2 weeks. I kept the parts wrapped in "saran" wrap. It should have been a disaster,
but it's sticking very well. I used Akzo-Nobel epoxy aerospace primer.
I really can't tell if the prekote even did anything, but since the paint is sticking, I'm not complaining.
Of course, I'm not flying yet, and the parts have not been really abused, so the paint could start
flaking off or peeling soon. YMMV.
I used prekote because I found it very hard to get alodine here in Switzerland, even though
one of my neighbors is the sales rep for Henkel (alodine manufacturer) in this area. He could get me
the touch-up pens, and that's all. For some reason, these Swiss guys don't want chromates in their
water. I don't get it!
I didn't follow the directions to the letter. I used tap water to rinse off the parts, and I didn't paint
them for about 2 weeks. I kept the parts wrapped in "saran" wrap. It should have been a disaster,
but it's sticking very well. I used Akzo-Nobel epoxy aerospace primer.
I really can't tell if the prekote even did anything, but since the paint is sticking, I'm not complaining.
Of course, I'm not flying yet, and the parts have not been really abused, so the paint could start
flaking off or peeling soon. YMMV.
Proper application
I am using Prekote and AKZO epoxy primer on my RV7 and I have spoken several times to the folks at Pantheon about application. I don't rinse with RO or DI water, I just use water from the tap, but what I am really careful about is not letting the Prekote dry on the surface before the rinse step. If it does dry, it needs to be re-wet with prekote, hit it lightly with the scotch brite pad, and then rinse. Alumiprep 33 has the same instructions regarding allowing it to dry on the surface being painted.
I apply as follows: Wet with prekote, scuff well with a red scotch brite pad (the Prekote will lather up nicely), wait two minutes, re-wet with Prekote, hit it again with the scotch brite pad and immediately do a good rinse.
Pantheon recommends priming within 24 hours of application.
I am using Prekote and AKZO epoxy primer on my RV7 and I have spoken several times to the folks at Pantheon about application. I don't rinse with RO or DI water, I just use water from the tap, but what I am really careful about is not letting the Prekote dry on the surface before the rinse step. If it does dry, it needs to be re-wet with prekote, hit it lightly with the scotch brite pad, and then rinse. Alumiprep 33 has the same instructions regarding allowing it to dry on the surface being painted.
I apply as follows: Wet with prekote, scuff well with a red scotch brite pad (the Prekote will lather up nicely), wait two minutes, re-wet with Prekote, hit it again with the scotch brite pad and immediately do a good rinse.
Pantheon recommends priming within 24 hours of application.
Last edited:
I did my VS with alodine & chromated epoxy but switched to prekote and AFS primer sealer since then for the HS & wings, which has been generally less work to apply & clean up, and basically no health/kids/pets worry.
I must say I do have some doubts about the effectiveness of the AFS product - it scratches much more easily and solvents take it off in a flash, so I'm using epoxy anywhere that wear or fluids might be a factor.
In hindsight I'd probably choose prekote and a non-chromated epoxy for the entire project as a good compromise between enviro considerations and performance.
I must say I do have some doubts about the effectiveness of the AFS product - it scratches much more easily and solvents take it off in a flash, so I'm using epoxy anywhere that wear or fluids might be a factor.
In hindsight I'd probably choose prekote and a non-chromated epoxy for the entire project as a good compromise between enviro considerations and performance.
Prekote and Deft
I have used Prekote followed by Deft primer which is water soluble. I find them very easy to work with and pretty much bullet proof once applied and cured. The deft is a has a time shortly after spraying that is easy to damage if you move the parts too soon, but once set, it just can't be taken off other than grinding it seems. I am very happy with the results and the two products
are very easy to use.
I have used Prekote followed by Deft primer which is water soluble. I find them very easy to work with and pretty much bullet proof once applied and cured. The deft is a has a time shortly after spraying that is easy to damage if you move the parts too soon, but once set, it just can't be taken off other than grinding it seems. I am very happy with the results and the two products
are very easy to use.
ijustwannafly
Well Known Member
No to revive an old thread but I'm not sure why you would say it has no corrosion prevention. It specifically lists corrosion prevention in one of attributes
rscooter
Member
Hi All
I and a fellow builder have used Prekote on our paint jobs. It's been over a year of flying for the both of us with a total of maybe over a 100 hours and can report as of now it's been great. Rick had his applied and painted at another shop than mine but we both used the Prekote that I bought from the PPG dealer. Mine is shot with Genesis Sherwin Williams and his I don't know but it was applied as instructed as specified and rinsed off with tap water.
I have had to do some repairs (my screw up)and just fixing things and it appears to have bonded very well. I still have over 2 gallons left from a 5 gallon pail. So if you can come out here you could use what I have left?( I won't send due to all the technical bull)
I was afraid of using it at first but now am completely satisfied with the product.
Scott
I and a fellow builder have used Prekote on our paint jobs. It's been over a year of flying for the both of us with a total of maybe over a 100 hours and can report as of now it's been great. Rick had his applied and painted at another shop than mine but we both used the Prekote that I bought from the PPG dealer. Mine is shot with Genesis Sherwin Williams and his I don't know but it was applied as instructed as specified and rinsed off with tap water.
I have had to do some repairs (my screw up)and just fixing things and it appears to have bonded very well. I still have over 2 gallons left from a 5 gallon pail. So if you can come out here you could use what I have left?( I won't send due to all the technical bull)
I was afraid of using it at first but now am completely satisfied with the product.
Scott
BillL
Well Known Member
Beware of what exactly is being said, here is the quote:
"and advanced corrosion protection on painted surfaces when used as part of a coating system."
Spending hours on the DoD report database yielded many test results. The "system" is a specific corrosion prevention primer over the prekote. IT, the primer, and top coat, provides the corrosion protection.
There are many "tests" for evaluation and many criteria per test, and many different alloys to protect. The scratch test then exposed to salt spray is the most revealing. I found 4 different salt spray test protocols.
Just about all of the tests showed good results on aluminum what did not contain copper - like 2024.
I did find one thorough test that approved prekote along with a specific primer and top coating and procedure. Even the scratch test. All the others I read (4-5) it failed. My conclusion - be very careful with prekote/primer/top coat system - or just use alodine and chromated Mil-Spec primer. Proper selection of the "system" apparently provides good corrosion protection with prekote. A lot has changed in the paint world since this thread started in 2005. To get the report google this :"AFRL-RX-WP-TP-2008-4012" removing the quotes, of course.
Like a lot of things - do the homework, "choose wisely" (Old Knight from Indiana Jones).
Last edited:
Vansconvert
Well Known Member
5 gallon un-opened can of Pre-kote for sale
I have an un-opened 5 gallon can of pre-kote for sale if anyone is interested.
Located between Milwaukee and Chicago.
I have an un-opened 5 gallon can of pre-kote for sale if anyone is interested.
Located between Milwaukee and Chicago.
ijustwannafly
Well Known Member
Dave
Im pretty sure you are referring to Eko prime. That is the only one part product Stewerts makes. I have used them both. The one part you referred to is not an epoxy primer. Its really just a wash primer. The Eko Poxy you refer to is actually a two part waster based epoxy primer. This has a catalyst like akzo. Its significantly thicker and heavier. It was originally intended for sea plane use according to dan from stewerts.
Just wanted to clarify. At this time Stewerts does not make a 1 part Epoxy primer.
