Ribs etch, alodine, and prime
With this round of parts etching and alodining we have made a number of improvements.
We used a dip bath to acid etch the parts. Previously our acid etch method was to take our cleaned parts out to the driveway and spray the acid etch solution onto the part from a simple squeeze spray bottle, scrub with a scotchbrite pad, and rinse with the hose. All this while working on the ground with rubber gloves on made for a miserable experience.
What we did this time was to mix up a batch of the acid etch solution (1 part PPG DX-533 / 3 parts water) of about two cups of acid and six cups of water. This was sufficient to cover the bottom of the dip bath. Then we dropped one rib at a time into the acid bath and scrubbed all surfaces with a scotchbrite pad. This was done on top of the bench in the well ventilated garage. It was much easier to dunk the part with full solution saturation and scrub, dunk and scrub, etc. Actually Tanya acid etched all of the wing ribs. After each rib or part was done in the acid scrub bath, we dunked it into a nearby trashcan full of water on the driveway, then sprayed it off with the hose and hung it up to dry.
To hang all of this stuff up to dry, we put clecos into the main spars which were up on the stands and hung the parts on the clecos. This was Tanya’s idea and it worked great. We used this for all steps including to hang up to dry after primer.
Alodining was a similar setup and process except without the scrubbing. I put 1.5 gallons of alodine (actually PPG DX-503) in the same bath fixture. This was just enough to fully cover a main rib by about 3/4″. Once the rib was done in the bath, it went to a fresh trashcan full of water. No need to spray off with the hose after the water dunk. And, hang up to dry.
For the rear spars, I etched them with the solution sprayed from a bottle. I also sprayed the alodine on them and washed it off. They sure didn’t come out very good, but that should be expected when you’re spraying alodine from a spray bottle. It just isn’t the same as dipping but there was no way I was making a twelve foot long dip setup.
After the alodined parts dried for a day, we setup the primer spray booth and shot primer. Since my last large primer batch, I bought a new Devillbis HVLP primer spray gun. I was not very happy with the results from the cheep Harbor Freight gun that I was using on the empennage parts. The $250+ that I spent on the new gun was, with out a doubt, worth every penny for me. It is so much easier to use and produces fantastic results with ease. I could go on about the gun because the difference in results is so great, but I’ll just leave it at that. Suffice to say, the new primer gun rocks!
