Cleaning & Priming 4130

[Jackal]

I am preparing to prime my empennage. It is easy enough to remove the light rust that has occurred during construction from the straight sections of the tubing, but the clusters are a bit harder. Even a small wire brush doesn't get to all of the areas. I don't want to sand blast them if I can avoid it because of getting sand in the open ends of the stab spars, and possibly other areas where it will be difficult to remove, or possibly remain forever, gathering moisture.

Furthermore, Tony Bingelis writes that mechanically removing all visible rust does not eliminate rust particles forced into the pores of the metal and that 4130 must have the rust neutralized with a chemical "metal conditioner". Will this conditioner also remove the rust in the tight spots?? What is this conditioner and where can it be purchased??

In the real world of Hatz what has been done in the past. Have those who have failed to use chemicals had their paint raise up in areas indicating active corrosion beneath. Have some even gone so far as to leave small amounts of light rust in the tightest corners of the clusters and primer and paint over it with the paint still adhering years later???

I'd appreciate any input from those of you with primed/painted fuselages - especially if something went wrong.

[hatz215]

Personally, I would poke something in those open ends and sandblast.

Steve G
N85DG

[Jackal]

It would be pretty easy to seal off the open ends, but when doing the same to the fuselage which will follow I am more concerned about the attaching brackets (such as the landing gear and lower wing root and cabanes, etc.). The clusters without brackets have no place to really collect sand (or glass beads) but the brackets that are not welded on all sides have crevices where sand can get, and I don't see how it can ever really be gotten out.

The same situation is somewhat true of the empennage as I welded the bent up (channel) ribs only on one side, so the other side (insides of channels) could collect sand.

I actually have sand blasting equipment of my own, so doing it is no problem, just not sure its the right thing to do.

Thank you for your input,

-Jackal

[jwhanson]

Hi Jackal,
Sit down, take a few deep breaths, then sand blast it and paint it. Everything will be fine. Try to paint as soon as you can after sand blasting.
John Hanson

[JBMoore]

Very good advice!!!
There will be plenty of times when "sit down, take a few deep breaths" will help solve the problem or clear your head.

Jeff Moore

[schnepel]

Good advise yes indeed. After blasting use an epoxy primer such as Randolph or Polyfiber manufactures. If you are preparing the fuselage, the lighter the primer/paint the more easily cracks in welds will show.