Stainless Steel and Aluminum

[d_wildemann]

Previous owner of my Trillium repacked the windows. When he reinstalled them, he used stainless screws. The frames are aluminum. I am now getting rust around the screws. Anybody have a solution?

Thanks.

-Don

[Dale]

Previous owner of my Trillium repacked the windows. When he reinstalled them, he used stainless screws. The frames are aluminum. I am now getting rust around the screws. Anybody have a solution?

Thanks.

-Don

Hi Don,
In the marine idustry, stainless and brass screws are the only type allowed on aluminum hulls and pilot houses because they act like similar metals and should not corrode. Perhaps the screws are your trailer are not a good quality stainless steel. True stainless or brass can be had at a good marine store, or you can always use aluminum rivets.

[Byron Kinnaman]

I don't know a lot about galvanic reactions, but this site might help.

If I read this correctly stainless steel and aluminum might not be very compatible.

[gillian s]

an isolator should be used whenever dissimilar metals are in contact to avoid galvanic corrosion. i use a product called tef-gel, it is sort of a paste and comes in a little bottle like nail polish or in a larger tube. dip the screws, once cleaned up a bit in this stuff and refasten and interaction between the alu/ss will cease.

[Steve L.]

Actually, stainless and aluminum don't go together very well. Eventually the stainless screws can be become difficult to remove or could break in place. Stainless screws in aluminum should be coated in anti-seize compound to "break" the galvanic connection.

We should keep in mind that there are different grades of stainless with various levels of corrosion performance. For example, not all stainless is non-magnetic.

Corrosion of stainless parts isn't (usually) rust, but pitting. I used stainless threaded rod for an antenna bumper mount that I fabricated and the stainless appeared to rust on the cut ends, but is more likely bits of steel from the hack saw blade left embedded in the cut end.

I'm told that you can also harm the stainless performance by overheating the stainless during the cutting process but I don't know if hacksawing it qualifies as overheating.

It's just me, but I'd look elsewhere than the screws for the source of rust.

[Donna D.]

I pulled the door window out of my Scamp and when I went to purchase new fasteners...the guy at the hardware store told me to use nylon washers between the head of the screw/bolt and the aluminum frame. Since the washers are white and the window frame is black, he further recommended dyeing the washers using plain-ole black Rit dye...available just about anywhere.