Paul, in addition (as you know) the type of aluminium has a factor in your decision too. Say 2024-T3 (Van's, Cessna, most Al RPT aircraft etc etc) versus 6061-T6 (Rans, Sonex, Al boats).
Very diplomatic presentation on what is known as a touchy subject. Your example regarding quick builds makes me think that perhaps the company that sells these pre-primed kits may not necessarily be endorsing the priming processing, but find it a necessity for protecting their product from salt water contamination during shipment from the Philippines.
I've been using that self-etching primer that comes in the rattle cans for metal. It works great, and is suspiciously similar to what I remember zinc chromate was like. For Poly Fiber, it says to use an epoxy primer. To avoid that, I got a can of appliance epoxy in the rattle can, which dries slow and stays tacky. Then sprayed poly fiber paint over it and it came out great.
To expand on Jason's comment, 6061-T6 is much more corrosion-resistant than other alloys. Another alternative primer you didn't mention is using Cortec primer on mating surfaces of parts - dilutes with water, brushable, and relatively non-toxic.
Another big area of priming is when attaching two dis-similar metals (Aluminum to stainless steel). Rather than moisture corrosion, you are protecting against electrolysis. I use a rattle can Zinc Phosphate which is still available. The theory is that the Zinc in the primer draws away the electrolysis from the metal. If I lightly sand and then clean with acetone, the primer adheres extremely well.
When ever riveting new parts together your should aleast etch prime both surfaces in lap joints & seams or where ever moisture or water can get in to start corrosion. This is very easy when working with new metal just clean with solvent & spray. Old metal wire brush, scotch brite or etch first.
I have worked on commercial aircraft for over 50 + years and never once seen unprotected structures and any replacement parts ordered from the aircraft manufacturer arrived pre primed. Furthermore, any repair work called for priming the effected surface areas.
I was Shocked to see a T-Handle left in the Lathe's Chuck in the background. Bad Practice. The possibility of trauma to a new kid in the shop is likely.
And no-one mentions acf-50 or corrosion-x why not? If you prime incorrectly, that might accelerate trapped corrosion. If you use acf-50 or corrosion-x, you just apply it periodically over the years and it eventually dissipates, but it is very simple to apply. Certainly much less work than priming.
You are showing inside priming that only runs along seams and rivet lines. Why are you not coating all the metal? Corrosion does not happen in the bare areas?
You believe wrong You missed on this video. sorry. There are two types of primers. There are sealing & non sealing primers. Sealing primer doesn't not require a top coat to protect against corrosion. Non sealing like that "Raddle Can self etching" is a primer that requires a top coat to protect against corrosion. YES I am right correct & Yes I ahve contacted RustOlem directly about their product. That exact product specifically. No need to say thankx
I use EPC-2 primer from Endura. It is a true sealing primer. However it is not user friendly. Not even a tiny bit user friendly. I love Aircraft Spruce
Paul, in addition (as you know) the type of aluminium has a factor in your decision too. Say 2024-T3 (Van's, Cessna, most Al RPT aircraft etc etc) versus 6061-T6 (Rans, Sonex, Al boats).
Very diplomatic presentation on what is known as a touchy subject. Your example regarding quick builds makes me think that perhaps the company that sells these pre-primed kits may not necessarily be endorsing the priming processing, but find it a necessity for protecting their product from salt water contamination during shipment from the Philippines.
Good information, thank you. Resale value may be an important factor too.
Great Video Series! We're sharing all of them as they come out.
I've been using that self-etching primer that comes in the rattle cans for metal. It works great, and is suspiciously similar to what I remember zinc chromate was like. For Poly Fiber, it says to use an epoxy primer. To avoid that, I got a can of appliance epoxy in the rattle can, which dries slow and stays tacky. Then sprayed poly fiber paint over it and it came out great.
Heading to an EAA Sport Air workshop on sheet metal tomorrow. I've loved the series and learned a lot but nothing beats hands on.
Great series, please continue !
What? The series is ending??? Noooooooo! How about round 2? These are great, and Paul is GREAT.
To expand on Jason's comment, 6061-T6 is much more corrosion-resistant than other alloys. Another alternative primer you didn't mention is using Cortec primer on mating surfaces of parts - dilutes with water, brushable, and relatively non-toxic.
Another big area of priming is when attaching two dis-similar metals (Aluminum to stainless steel). Rather than moisture corrosion, you are protecting against electrolysis. I use a rattle can Zinc Phosphate which is still available. The theory is that the Zinc in the primer draws away the electrolysis from the metal. If I lightly sand and then clean with acetone, the primer adheres extremely well.
So helpful! Thank again for all the knowledge!
Just a note. You could also mix your own epoxy primer and shoot with prevails and have less cleanup.
Great information! Love your program.
When ever riveting new parts together your should aleast etch prime both surfaces in lap joints & seams or where ever moisture or water can get in to start corrosion. This is very easy when working with new metal just clean with solvent & spray. Old metal wire brush, scotch brite or etch first.
Very well presented.
Wait… so what did they prime the Space Shuttle with?!
I have worked on commercial aircraft for over 50 + years and never once seen unprotected structures and any replacement parts ordered from the aircraft manufacturer arrived pre primed. Furthermore, any repair work called for priming the effected surface areas.
I was Shocked to see a T-Handle left in the Lathe's Chuck in the background. Bad Practice. The possibility of trauma to a new kid in the shop is likely.
I thought self etching primer is porous? It doesn't seal the substrate.
And no-one mentions acf-50 or corrosion-x why not? If you prime incorrectly, that might accelerate trapped corrosion. If you use acf-50 or corrosion-x, you just apply it periodically over the years and it eventually dissipates, but it is very simple to apply. Certainly much less work than priming.
You are showing inside priming that only runs along seams and rivet lines. Why are you not coating all the metal? Corrosion does not happen in the bare areas?
Some people only prime where moisture can be trapped.
24 is in fact not prime :)
You believe wrong You missed on this video. sorry. There are two types of primers. There are sealing & non sealing primers. Sealing primer doesn't not require a top coat to protect against corrosion. Non sealing like that "Raddle Can self etching" is a primer that requires a top coat to protect against corrosion. YES I am right correct & Yes I ahve contacted RustOlem directly about their product. That exact product specifically. No need to say thankx
I use EPC-2 primer from Endura. It is a true sealing primer. However it is not user friendly. Not even a tiny bit user friendly. I love Aircraft Spruce
"I'm gonna be dead before it will ever corrode." We all know a guy that chose his wife by that thought process.
I attended a talk by a couple of Vans engineers and they poo-pooed priming as silly