The state of the sheath was worse then I thought too. It was cracked and split at 2 points and Skaukraft warned me by saying that these sheaths usually were not made of leather, buth of some sort of pressed cardboard like material.
Some internetsearching showed that the knife, a Mora Classis, usually had an unpainted handle coming with this sheath and a painted handle with a plastic sheath. So appearantly this is not a original mix either. Not that it matters, really.
The first thing I did was to gently clean up the sheath and then rub it with a little saddlegrease. This brought back the colour immediately, making it look like leather. The sheath itself is very hard and springy, as if it were shaped wood. Maybe it is a leather/cardboardcomposite? I don't know. All I know is that the sheath responded well to the greasetreatment, gained colour and retained its shape.
Next I took the sheath apart. I unclipped the metal clip at the back, took off the torn loop and took out the rotten stitching too. After that I sanded the entire knife, both handle and blade. Some of the red paint has gotten deep into the grain and is near to non-removable. The pitting at the knife's tip is more serious then I had initially thought it would be. This called for a chemical solution; a vinegarbath.
Befor that I oiled the handle with vegetable oil, so it would be a bit protected from staining by handling or the vinegar.
While the blade was bubbling away in the vinegar (due to the chemical reaction it really does bubble) I turned my attention to the sheath. Taking out the rotten stitching meant restitching and here's where the sheathmaterial had a little surprise in store. Since it is so hard I could not reuse the original stitchingholes. I guess the sheath is wetformed and stirched immediately afterwards causing the material to reform around the stitches. I had to make new holes. During that procedure I found out that it indeed does behave like cardboard, so after initially resisting you it suddenly gives way, leaving big holes. So care needs to be taken here. Also when stitching the holes tend to tear, when the thread is being drawn to tight. I used a saddlestitch, by the way, meaning working with 2 needles simultaniously. You thread the needles through the same holes, but in opposite directions.
I melted an amount of wax, using the au bain marie-method; a tin of wax, placed into a pan with water on the stove. This way the wax is not directly heated, does not overheat and thus the risk of ignition is greatly reduced. It also makes it easy to maintain control over the wax' temperature, so you don't easily burn yourself using it.
When the wax had melted I dipped the lower half of the sheath into it, in several dips, letting the wax set between each dip. This wat the larger openings in the sheath are all filled up and the sheath is watertight. It is the same principal as with making leather flasks, tankards and such. After setting the excess wax was gently scraped off and I rubbed the sheath with some cloth. The result was very pleasing! The sheath got a nice sheen to it and indeed had the holes in the bottom been plugged firmly. The wax remained sticky however, due to the handling and the high (summer)temperatures in the kitchen. So after I dipped the tophalf of the sheath I put it in the fridge, cooling the wax to make it solid and more easily workable.
In the meantime I also made a new beltloop. The singleslit buttonloop didn't look to practical, so I made a dualslit beltloop. Simply a matter of cutting a piece of leather to shape. By foulding it double and holding it into place, it'll be nicely symetric. The slits have circulair punchouts, so they do not tear so easily.
I took the knife out of its bath, in which it had been sitting overnight. The blade crealy showed the 2 different sorts of steel used; the edge had a much darker patina then the rest. An unpleasant surprise was, again, the discolouration of the wood, even without it toughing the vinegar. The capillary effect, I guess...
As a final stage I sharpened it and was surprised by how easy the knife took and edge... and a good one!!
And from now on, this knife will be riding the oldschool-bag, accompanying the birchbarkcontainers and wooden eatingutensils. it'll be used as it was meant to, instead of rotting away or lying in some drawer... forgotten.