Alodine method ...
Ok, I've done more experiments and I'll try to answer my own question, and share my experiences so you smarter guys can avoid my mistakes ... I'm not a chemical engineer, or professional painter, so please forgive my simple-minded aproach to ths little problem.
I sent emails to Henkle (the manufacture of Alodine 1201) asking about the "blue problem". They wouldn't answer the questions I asked ... they simply asked for the batch number from the Alodine bottle, then told me that my bottle was over two years old, too old, and I should buy a new bottle.
Not really pleased with the non-answers from Henkel, I bought new bottles of alodine and prep from DuPont, the 225S and 226S products.
Using the new DuPont chemicals, I was real careful to clean and double clean everything. I used new cleaner/prep chemicals, new alodine chemicals, and new brushes. But still the same "blue problem" came back. If anything, the blue was more pronounced ... in fact the better I cleaned things, the more blue I got. (So much for the Henkle's "... old chemicals" answer!)
By observing things very carefully, I think I've finally figured out the problem. First, I noticed that the alodine did not seem to be contaminated; it looked nice and yellow when it went on, and was still yellow when it rinsed off. Second, I was pretty sure I had eliminated the possibility of contamination on the aluminum; by careful cleaning and noticing that the blue splothes and streaks bore no resemblence to any noticable cleaning marks. Next, I noticed that the aluminum where the alodine made first contact usually turned a yellow/brown, and the areas where the alodine was spread to with the brush had turned blue. Finally, I realized that the blue splotches matched the brush strokes, and the drip patterns of the way the alodine was applied!
It seemed that the blue was being created as an interaction between the good clean aluminum and the good clean alodine. This was counter to my hunches that there was a cleaning, bad chemicals, or contamination problem. (Along the way I tried using different applicators, thinking that the black foam brushes may be "bleeding" die into the alodine. I tried different rubber gloves, thinking the black rubber may be interacting with the alodine.)
I have finally concluded that the blue problem was caused by my application technique. Simply, I was putting too little alodine on the aluminum. When the parts are dipped then there is lots of alodine to interact with the aluminum. When the parts are brushed, there is only a very thin film of alodine on the aluminum.
The directions for applying the alodine advise that you should not allow the alodine to dry on the aluminum. I was careful to make sure it didn't get dry. Apparently, a very thin film of alodine wetness is already "too dry" and causes this blue problem ... this was my mistake!
I was getting my foam brush wet with alodine and then quickly spreading it over the entire surface, then dipping my brush and adding more alodine and spreading more alodine to keep it wet. I now believe this vigorus brushing technique to spread the alodine over the surface was getting the wet film too thin and causing the problem.
I haven't figured out how to brush alodine correctly yet. For now, I'm going to stick with dipping.
You might think the the Henkle support guy could have said something like, "if the alodine is allowed to dry on the aluminum you will get a blue stain".
I found this mis-application of the product (using a brush as suggested in the product's instructions) so easy to create that I can't believe I'm the only one who has had this problem.
I sent emails to Henkle (the manufacture of Alodine 1201) asking about the "blue problem". They wouldn't answer the questions I asked ... they simply asked for the batch number from the Alodine bottle, then told me that my bottle was over two years old, too old, and I should buy a new bottle.
Not really pleased with the non-answers from Henkel, I bought new bottles of alodine and prep from DuPont, the 225S and 226S products.
Using the new DuPont chemicals, I was real careful to clean and double clean everything. I used new cleaner/prep chemicals, new alodine chemicals, and new brushes. But still the same "blue problem" came back. If anything, the blue was more pronounced ... in fact the better I cleaned things, the more blue I got. (So much for the Henkle's "... old chemicals" answer!)
By observing things very carefully, I think I've finally figured out the problem. First, I noticed that the alodine did not seem to be contaminated; it looked nice and yellow when it went on, and was still yellow when it rinsed off. Second, I was pretty sure I had eliminated the possibility of contamination on the aluminum; by careful cleaning and noticing that the blue splothes and streaks bore no resemblence to any noticable cleaning marks. Next, I noticed that the aluminum where the alodine made first contact usually turned a yellow/brown, and the areas where the alodine was spread to with the brush had turned blue. Finally, I realized that the blue splotches matched the brush strokes, and the drip patterns of the way the alodine was applied!
It seemed that the blue was being created as an interaction between the good clean aluminum and the good clean alodine. This was counter to my hunches that there was a cleaning, bad chemicals, or contamination problem. (Along the way I tried using different applicators, thinking that the black foam brushes may be "bleeding" die into the alodine. I tried different rubber gloves, thinking the black rubber may be interacting with the alodine.)
I have finally concluded that the blue problem was caused by my application technique. Simply, I was putting too little alodine on the aluminum. When the parts are dipped then there is lots of alodine to interact with the aluminum. When the parts are brushed, there is only a very thin film of alodine on the aluminum.
The directions for applying the alodine advise that you should not allow the alodine to dry on the aluminum. I was careful to make sure it didn't get dry. Apparently, a very thin film of alodine wetness is already "too dry" and causes this blue problem ... this was my mistake!
I was getting my foam brush wet with alodine and then quickly spreading it over the entire surface, then dipping my brush and adding more alodine and spreading more alodine to keep it wet. I now believe this vigorus brushing technique to spread the alodine over the surface was getting the wet film too thin and causing the problem.
I haven't figured out how to brush alodine correctly yet. For now, I'm going to stick with dipping.
You might think the the Henkle support guy could have said something like, "if the alodine is allowed to dry on the aluminum you will get a blue stain".
I found this mis-application of the product (using a brush as suggested in the product's instructions) so easy to create that I can't believe I'm the only one who has had this problem.-
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Alodine blue on aluminum
Loosenut:
I had the same issue with Alodine on my wing ribs. I am guessing that it was due to the chemical getting old. I keep my alodine in a 5 gallon bucket between uses. My guess it has both reacted with aluminum and with the air too many times.
I decided to switch over to Brad's (rv7factor.com) approach (PPG Primer) b/c the alumiprep/alodine method is way too time consuming, way too toxic and of late I am not thrilled with the results. Everything came out great with the tail, but not with the wings. Of course you can't tell now that the ribs have Akzo on them, but I figured if I wasn't happy with the results, I might as well give up on the process.
Antony
I had the same issue with Alodine on my wing ribs. I am guessing that it was due to the chemical getting old. I keep my alodine in a 5 gallon bucket between uses. My guess it has both reacted with aluminum and with the air too many times.
I decided to switch over to Brad's (rv7factor.com) approach (PPG Primer) b/c the alumiprep/alodine method is way too time consuming, way too toxic and of late I am not thrilled with the results. Everything came out great with the tail, but not with the wings. Of course you can't tell now that the ribs have Akzo on them, but I figured if I wasn't happy with the results, I might as well give up on the process.
Antony
Antony,
I was trying really hard to figure this Alodine stuff out.
I didn't want to give up on it just because I was too stooopid and doing it wrong. So, I wasted a lot of time trying different techniques. I too was suspicious of "old" or "contaminated" chemicals. However, I convinced myself this wasn't the cause of my "blue staining" problem. I bought new chemicals and had the same "blue staining" problem when I brushed ... then I used the same old and same new chemicals with a dunk and it worked fine.
Basically, I've come to the conclusion that it works ok if I dunk the parts and it doesn't work if I try to brush it.
Now I feel like I've figured out how to use the stuff ... how to clean, dunk, rinse, gas mask, rubber gloves, goggles, ventilation, etc ... and I'm with you on this, this stuff is a mess, too time consuming, too toxic, results look so-so.
I'll use the Alodine when it seems the best for a particular situation, but, it will not be the general, overall, go-to stratagy.
++Harold
I was trying really hard to figure this Alodine stuff out.
I didn't want to give up on it just because I was too stooopid and doing it wrong. So, I wasted a lot of time trying different techniques. I too was suspicious of "old" or "contaminated" chemicals. However, I convinced myself this wasn't the cause of my "blue staining" problem. I bought new chemicals and had the same "blue staining" problem when I brushed ... then I used the same old and same new chemicals with a dunk and it worked fine.
Basically, I've come to the conclusion that it works ok if I dunk the parts and it doesn't work if I try to brush it.
Now I feel like I've figured out how to use the stuff ... how to clean, dunk, rinse, gas mask, rubber gloves, goggles, ventilation, etc ... and I'm with you on this, this stuff is a mess, too time consuming, too toxic, results look so-so.
I'll use the Alodine when it seems the best for a particular situation, but, it will not be the general, overall, go-to stratagy.
++Harold
RV-7A wings