Eriselle
Member
Hello,
I'm in the early stages of planning an upcoming RV-9A build, which will be my first build. A lot of information on the internet about etching and alodining is confusing. I've spent hours searching the forums here and elsewhere. I'll probably ask a bunch of questions over time, but here are a few specific questions I have right now:
1.) https://www.pilotsofamerica.com/community/threads/alodine-or-no-alodine.118147/post-2712823
This post states, "Aluma-prep is an etch, so is alidine" (spelling as-is in the post).
Is this actually a correct statement that alodine is an etch? It would make more sense to me if this is not correct, because otherwise why would you need to acid etch before alodining if alodine is already an etch?
2.) I've read that alodining weakens the metal because the chemically altered surface of the aluminum is weaker than the unaltered aluminum. This would be, as far as I understand it, similar to how anodizing weakens the metal, for the same reason. I've read that the wing spars from Vans compensate for the anodizing weakening intentionally, as it is a known quantity of weakening.
Is this understanding of the weakening caused by alodining correct, and is it a significant factor? How much of a factor is it? Is this planned on by Vans' design?
3.) It is my understanding that acid etching creates a less smooth surface by eating away at smooth surfaces, which helps the primer to bond better. However, an amount of the prep work for parts is removing sharp edges, corners, and deep scratches. It is my understanding that any of those kinds of non-smooth or curved edges become failure points. Maybe I'm overthinking this, but wouldn't taking a smooth surface and etching it to be non-smooth weaken the metal, in addition to the fact that simply removing material would assumedly weaken it? Is this not an issue because the amount of material we are talking about, and the depth of the etching is very light in comparison to what would be considered a "deep scratch"?
4.) https://www.rvplane.com/priming/ This link discusses using an electric engraver to mark your parts since the priming prep process will remove your sharpie markings. Is this a concern for weakening the parts?
Thank you for your time and knowledge.
I'm in the early stages of planning an upcoming RV-9A build, which will be my first build. A lot of information on the internet about etching and alodining is confusing. I've spent hours searching the forums here and elsewhere. I'll probably ask a bunch of questions over time, but here are a few specific questions I have right now:
1.) https://www.pilotsofamerica.com/community/threads/alodine-or-no-alodine.118147/post-2712823
This post states, "Aluma-prep is an etch, so is alidine" (spelling as-is in the post).
Is this actually a correct statement that alodine is an etch? It would make more sense to me if this is not correct, because otherwise why would you need to acid etch before alodining if alodine is already an etch?
2.) I've read that alodining weakens the metal because the chemically altered surface of the aluminum is weaker than the unaltered aluminum. This would be, as far as I understand it, similar to how anodizing weakens the metal, for the same reason. I've read that the wing spars from Vans compensate for the anodizing weakening intentionally, as it is a known quantity of weakening.
Is this understanding of the weakening caused by alodining correct, and is it a significant factor? How much of a factor is it? Is this planned on by Vans' design?
3.) It is my understanding that acid etching creates a less smooth surface by eating away at smooth surfaces, which helps the primer to bond better. However, an amount of the prep work for parts is removing sharp edges, corners, and deep scratches. It is my understanding that any of those kinds of non-smooth or curved edges become failure points. Maybe I'm overthinking this, but wouldn't taking a smooth surface and etching it to be non-smooth weaken the metal, in addition to the fact that simply removing material would assumedly weaken it? Is this not an issue because the amount of material we are talking about, and the depth of the etching is very light in comparison to what would be considered a "deep scratch"?
4.) https://www.rvplane.com/priming/ This link discusses using an electric engraver to mark your parts since the priming prep process will remove your sharpie markings. Is this a concern for weakening the parts?
Thank you for your time and knowledge.
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