Corrosion!

My wings are complete and ready for priming. The kit is two years old. On removing the blue plastic I have found some corrosion on the skins but only in the area of the manufacturers spec. details. I assumed the ink is water based and corrosion is developing underneath the plastic post manufacture.

I am planning to scotchbrite, and acid etch prime. On a trial area of corrosion after using the fine (grey) scotchbrite the Alclad dulls off to a very dark grey. Nothing will remove this stain, even if I continue scotchbrite I had hoped to remove all of the corrosion prior to priming now I'm not sure if I'm doing more harm than good!!
The question is what is the best technique for dealing with this type of corrosion?
Do the areas of corrosion have to be completely removed prior to priming or does the process of acid etch combat further corrosion development?

Paint and finish solutions greatly received.

Andy use red Scotchbrite. The grey is waaaay too fine and in my experiences pretty much polishes the material. The red will give you much better surface for your primer/paint to adhere to.

-Jeff

Andy,
If the corrosion is advanced, use the maroon (Jeff calls it red) medium grit ScotchBrite discs. The gray discs are extra fine grit and won't do much. I prefer to use the blue, fine grit discs for most deburring and light scratch/corrosion removal. The blue discs will allow removal of the corrosion with less chance of removing the Alcad surface.
I would also suggest that you Alodine the corrosion affected areas as a minimum. If you live in a humid environment, doing less, will mean going back and doing this job again in 4 years, .
Charlie Kuss
PS The Germans have a saying. "The lazy man works the hardest".

I had that problem too....usually along the edges. You know what works great after the Scotchbrite (and a wipedown with MEK)? The Alodine pen.

Thanks for the responses. All very useful. I'll try the "red scotchbrite" and check the results.

Corrosion - if you are new to building you might want to read this.

This issue has bugged me for quite a while. I first approached VANS about 6 months ago because to some extent its a built in problem. I have summarised the problem as I see it at:

http://gikoncnsdr.blogspot.com/

35 Year Old RV4 Kit parts with Corrosion

Just took ownership of 35 year old RV4 kit that was stored in tough environments (moisture, mice) and never taken out of the crating. The kit was packaged from Vans in newspaper and I think it held in some of the moisture which aggravated the moisture situation.

Good news is the prefabbed wing spars are looking great


Some parts have minor corrosion, others have pretty severe corrosion and some of the parts I will need to replace.

My plan is to use Azko-Nobel for most of the parts and Alumiprep & Alodine for fuel tank internal parts.

Question regarding the prep for each of these on parts with existing corrosion.

- For the parts with heavy corrosion, do I need to remove all the grey staining prior to Azko-Nobel application?

- For the tank parts that I will Alumiprep and Alodine, same question do I need to remove all grey staining prior to Alumiprep?

Prep

steve murray said:

Just took ownership of 35 year old RV4 kit that was stored in tough environments (moisture, mice) and never taken out of the crating. The kit was packaged from Vans in newspaper and I think it held in some of the moisture which aggravated the moisture situation.

Good news is the prefabbed wing spars are looking great


Some parts have minor corrosion, others have pretty severe corrosion and some of the parts I will need to replace.

My plan is to use Azko-Nobel for most of the parts and Alumiprep & Alodine for fuel tank internal parts.

Question regarding the prep for each of these on parts with existing corrosion.

- For the parts with heavy corrosion, do I need to remove all the grey staining prior to Azko-Nobel application?

- For the tank parts that I will Alumiprep and Alodine, same question do I need to remove all grey staining prior to Alumiprep?

Click to expand...

I would scrub with maroon scotchbrite and Alumiprep. You may be suprised how is eats corrosion. Just make sure to wear PPE and capture all the liquids. I made a sluice from a shower curtain. All the stuff drained into a big storage container. When it evaporated, the remaining gallon was taken to the landfill haz mat disoosal.
Also, try scrubbing with Maroon and Bon Ami. No haz mat issues and as good as alumiprep in my opinion.

Another reason to remove the stupid blue plastic!!!!

Gusmax said:

Another reason to remove the stupid blue plastic!!!!

Click to expand...

This kit is so old it does not have any plastic at all! The only part I have come across with plastic (white opaque plastic) is the wing rear spar. All other parts have been void of any plastic.

It was kind of fun looking at the newspaper from 1985 that was used to wrap the parts!