Practically Classics Forum

While mowing the lawn at the weekend I found a penknife i had lost last year! It has been outside since October! It's stainless steel so there was me thinking a bit of oil and i will have a handy spare pen knife.
no.
It has some white "corrosion" all over it that is a bit like lime scale (in look and feel) I have forced all the blades open and tried moving it around but it's really stiff.
Does anybody know what happens to stainless steel when left outside for 6 months and if it is possible to reverse it?

Some stainless steel will "Rust" but it doesn't flake like non stainless steels. The higher the chrome content, the more resistent it will be to rust. I would have thought a bit of steel wool would bring it up. Shimano Chain & Cable Lube (See http://cycle.shimano-eu.com/publish/con ... kshop.html) is an excellent penetrating lubricant.

Lucky you found it, and not the mower blades!

These pages might be useful...

http://www.allstainlessltd.co.uk/info/u ... ess_2.html

http://www.corrosionist.com/cleaning_st ... _steel.htm

I'm no metallurgist, but guess the deposits could be galvanic corrosion due to the knife being in contact with the soil itself, or possibly from the spring or pin in the knife being a dissimilar metal.

Best to avoid steel wool on stainless as it does tend to embed itself in the stainless and then rust (cleaned an old sink this way a few years back and it was never the same again )

Hope that helps.

I've cleaned stainless with steel wool, with no ill effects. I imagine the stainless, in the knife blade, would be harder than that used in a sink and also more highly polished.

darrencambs wrote:the deposits could be galvanic corrosion due to the knife being in contact with the soil itself

They could, however they could also be caused by caustic erosion if, when cleaned up, they leave small pitted areas behind. That assumes that the soil is alkaline in its nature though.
Once [the knife] has been opened, use a little graphite powder to keep it nice and free. Rubbing a soft (2B or similar) pencil on the hinge area should do the job.

Next: "My boomerang won't come back?"

JPB wrote:"My boomerang won't come back?"

I have NEVER been able to make a boomerang come back. i'm sure the ozzies cheat and use elastic!

I left the knife in the garage so i'll have a go at it on Saturday and see if i can persuade it to move freely. The soil is heavy clay, no idea if it is acidic or alcali, the only thing i grow in the garden is grass. I have brown fingers!

Clay is alkaline - very.

Ask me how I know

(We live in the Sussex weald, there's clay in the grounds of our house that's so pure it's blue, you could make pottery from it)

Never mind. I won't be heart broken if it can't be fixed but it costs nothing to try. (at the minimum i will have some spare screwdriver bits and a pair of tweesers!)
I'll let you know if i manage to cut my fingers off while working on it

Leave it in a pot of plus gas for a week and then give it a blast with an airline.

Sorry if this is going off topic but I was suddenly reminded of when I lost a cap off my head in the wind. It was during a period of bad weather and I was driving home. I had to stop, as the road was getting rather snowy and I wanted to let the front tyres down a bit (Mini), in anticipation of the mountain road. When I got out, the wind was worse than I realised and my cap flew over an embankment. I couldn't see where it had gone and the snow was deep.

A few days (Maybe a week later), as I approached the spot from the road below (The road, where it blew off, crossed via a bridge, the one I had to leave), I saw a sark spot on the snow drift. It was my cap (Frozen but in tact) . I had it dry cleaned and I still have it. It's always nice to get back something which you lost (Which reminds me I can't find my copy of the video shown below and it's no longer available...but there maybe one supplier who has one).