My apologies if this is a repeated thread.
What is the best way to clean the aluminium lens barrel of a Jupiter-8 lens?? I'm talking about the outside surfaces, and I'm not talking about chrome. To be more specific, there are some dark-grey areas which seem very hard - or impossible?? - to remove.
Your sugestions & recipes are most welcome. Any opinions about metal cleaners or procedures that I should not use are also important...
Thank you in advance
Joao
Okay, first you need to know about one of the properties of aluminum: When it has been heat-treated, or exposed to oxygen over a period of time, it forms a hard thin skin over a softer center. It is why aluminum is so hard to weld -- like welding an icecream sandwich. Well, this can also make it difficult to clean. If the stains in aluminum have penetrated the thin skin, then normal cleaning options (metal polishes and aluminum brighteners) won't work. The only thing to do is to use steel wool and remove a layer of aluminum (not as drastic as it sounds, since the skin is
very thin and the softer exposed aluminum beneath will eventually harden.
Now about cleaning options:
Metal polish:
NevrDull is my metal polish of choice. All metal polishes are abrasive, but this is less abrasive than most. NevrDull comes as a can full of cotton wadding, saturated with a low abrasive metal polish in an oil base. The oil base keeps it from drying out right away, so you don't get that fine powdered grit sifting into the crevices of your camera. NevrDull also works very well for brightening dulled and oxidized paint and for brightening those plastic viewfinder lenses you see on box cameras and some folding cameras. It is safe to use on those because they are not precision lenses (all they do is tell you where the camera is pointed), but you should NOT use it on a taking lens.
Aluminum brighteners:
These are acid treatments for more deeply stained aluminum and are mostly used these days by the trucking industry and by the Navy (for use on aluminum deck plates). One of the most polular is Alumabrite. Be very cautious with this stuff; it is a 50/50 mix of sulphuric and hydrochloric acids. Keep it well away from your glass and wear both eye protection and rubber gloves. It comes in a spray can, so you'd ordinarily need to also wear a dust mask to avoid inhaling the mist, but you will be using it with a small paint brush or Q-tips if you are using it on cameras. It penetrates the skin of the aluminum and literally eats the crud out of the metal (including oxidation stains). It works on aluminum kind of like Tarnex works on brass and copper.
Finally, we come to #0000 steel wool. This is the cleaner of last resort. After you have tried everything else and it hasn't worked, you can remove the outer skin (along with any stains and pits) with #0000 steel wool -- provided that the stains and/or pits are not so deep that removing them would thin the metal too much.
Sadly, some metals (including aluminum), once they have been stained very deeply or pitted beyond a certain point, just can't be cleaned.
