Hi peter, thanks for posting the pics. from what I can see, here’s my 2 peneth. Im assuming that like many, you don’t have access to blasting kit, or the finances for deoxidine, allochrome, alodine etc, bead media etc. We deal with plenty of corossion like that at GAM. quite frankly much of the time we just cannot be bothered with the hassle of getting out all the blasting kit etc. 9-10 times for these types of corrosion, we remove 99% of it with mechanical means, such as emery paper, scotch bright, flap wheels etc, being careful to only remove the corrosion and not surrounding material, where we can. What is then importatnt is effective chemical treatment to kill what is left. Generally for the materials and corrosion issues you have posted, any phosphoric based solution applied for 20-30 minutes (40-50% solution) will dissolve stuborn corrosion on aluminium, and prepare the surface, after you have removed most of it manually. some times you may need to do it twice. the books will tell you NEVER EVER user phosphoric solutions on Magnesium based parts. Well you can take that with a pinch of salt. We treat Mag parts often with phosphoric based methods. So long as you thoroughly wash off the solution afterward, there really is no problem at all. blasting won’t always remove the corrosion in deeply pitted areas, magnesium parts being a prime example, and chemical is then the only way to get at it. As for the solutions, if you can afford it, then Deoxidine is very effective, if you can’t afford it, then plain old phosphoric acid, diluted to 40-50% will suffice, thoroughly washed off afterwards. quite often many of the auto shop rust curers have 20-30% phosphoric acid in them, and will suffice, all be it requiring 4-5 applications, because they are not strong enough. for flaky corrosion, you have no choice but to remove it all until you are back to clean metal, then the normal methods apply.
if you can get allodine or allochrome 1200 to prepare the surface before painting great. otherwise a good quality etch prime and top coat will suffice. if you don’t want to paint it, coat it in acf 50. if you cant afford that, good old wd40 mixed with clear wax oil, will suffice for parts on display inside. dinditrol clear cavity wax is also very efective, available from classic car dealers. if the surface is clad, often you will have no choice but to remove the clad, to get rid of the unsightly corrosion. the problem you then have is that the panel underneath will rot fast, normally because they have a high copper content. in this situation a coat of clear etch prime (like laquer) will protect it, or allochrome, if you dont care about it being yellow afterwards.
No doubt I will get flamed for this advise, but, I am walking the walk on a variety of old millitary aircraft regularly, and I am being realistic about what you have access to, with regards to time, manpower, materials, tools and money. Ask any of the brunty lads for Vixen, bucc, lightning etc and I guarantee you, that the above methods are used all the time effectively, on a budget. We don’t all have access to funds like Duxford, Hendon etc for fancy blasting cabinets, gallons of deoxidine, allochrome, acf50, paints etc. whilst I agree with much of the advise about blasting, it’s inconvenient, expensive, hassle, and beyond the scope of most poorly funded projects. The above methods do work too.
if you have access to the cabinets etc, then great!
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