[ QUOTE ]
AilSnail said:
I have a big hunk as well as a small 15w, the big 80w has one small dot where it is capable of melting the solder. I tried scraping off the corrosion, but it helped only temporarily. Is there hope for it?
[/ QUOTE ]
You could sand off the corrosion and use progressively finer grit (up to 600) to get it nice and polished smooth, then "tin" it with solder, turn off heat and wipe it with a cloth until only a thin coat of solder remains (should be a nice silve-gray color covering the entire working tip), thereby "plating" it to prevent further corrosion.
I use a small tub of tip cleaner I got from Radio Shack that I use for this purpose, has other ingredients to clean and "plate" the soldering iron's tip. The corrosion layer does not conduct heat nearly as well (if at all).