Prior to priming, all the aluminum airframe parts will be treated with Sanchem CC-6100 which is a cold conversion process similar to Alodine but without the nasty environmental and personal hazards. The process converts molecules of aluminum near the surface into a corrosion resistant form which will then be protected with an epoxy primer. For the start of the RV-12 project Sanchem CC-6100 will be used but DOG Aviation’s R&D department is looking into switching over to Sanchem CC-3400 for the wings where there are lots and lots of parts.
In an effort to not waste the chemicals I did not mix up a large batch … only mixed around a cup or so. First the parts are cleaned with a part C cleaner using a Scotch-brite pad and rinsed in distilled water. Next the part is exposed to the CC-6100 solution for 60 seconds and rinsed in distilled water. I noticed that small parts which could be kept submerged turned out looking better than parts having the solution brushed on. The golden finish was more even looking … the longer parts which were brushed with the solution tended to have streaks. I suppose if I were not priming and leaving the metal bare, I would not be pleased with the overall look of the brushed parts ... but since I plan to epoxy prime it is not a big deal. That said, if I don’t switch over to the CC-3400 for the wing ribs I will try to make a tray just large enough for the ribs and mix enough solution to make sure the ribs are totally submerged.
The CC-6100 and CC-3400 processes each have their own advantages and disadvantages but the end results are the same. Both products require a wash/activation which uses a mild cleaner that is scrubbed onto the part with a Scotch-brite pad until a break free surface is obtained. (Break free means the water sheets evenly on the surface of the part and does not bead up). CC-6100’s downside is once mixed (50-50 part A and part B), it has a shelf life of only 8 hours meaning … mix only what you can use up because any leftover solution should not be stored more than 8 hours. Upside, mix it at room temperature and it is ready for use by either immersing the part into the solution or wiping the part with a brush, sponge or rag. The conversion happens in seconds. The CC-6100 solution also neutralizes any cleaner left over from the cleaning/scrubbing phase.
Sanchem CC-3400 is a bit more involved and more suited for manufacturing environments because there are temperature requirements. There is an Alkaline cleaner bath that requires being kept at 100 to 120 degrees F and the CC-3400 solution requires being kept at 135 to 140 degrees F. The upside is there is not a shelf life on the mixture so you can keep using it over and over again until the chemical is depleted and no longer converts the aluminum. Another upside is one gallon of CC-3400 makes 11 gallons of solution.
