After leaving the handle scales in the ammonia overnight, I took them out the next day, washed them in running water and quickly dried them. First by letting them for an hour above the stove in my workshop and when they were nearly dry, heating them carefully in 10 sec intervals in the microwave until there was no steam coming out. I do not count this time into the manufacturing time, because I have been doing it this way only to be able to proceed quickly and get the knife done this weekend. Normally I would let it dry by itself.
When dried, the scales had to be fitted to the handle – that is done by carefully sanding the faces that are glued on the tang on a flat stone as long as it takes to get them nicely flat. Then I screwed the handle scales without the blade together again and sanded and polished the two forward facing facets, because once the scales are on the tang, nothing can be done about them.
As far as the metal goes, I cleaned most of the scale from the tang with 80 grit sandpaper and then I cut two pins from 6 mm brass rod, hammered them through the holes in the tang and tried whether the whole assembly fits together without unseemly gaps. I was prepared to eventually sand a bit here and there, but it was not necessary, it fitted nicely. So I slathered generous amount of quick drying epoxy cement on all adjoining surfaces and squeezed the whole assembly gently in the vice. I cleaned the epoxy that got squeezed out, first by scraping of the excess with a piece of wood and second by washing the blade with paper towel soaked in alcohol. A piece of epoxy on the back and belly of the handle are not a problem, since those areas will be sanded anyway, but a real care must be taken in cleaning the blade and the forward facing facets of the scales thoroughly, because again, any mistake there cannot be easily corrected.
The epoxy that I was using was hardening quicker than I was happy with, but our local Baumarkt has “optimized” its wares selection a few years ago and they are only selling quick-setting epoxies now and I will probably have to order some slowly setting epoxies over the internet. I got lucky and I managed to get everything important clean before the glue set, but it was a race with time. That means I could not make any pictures of that process, so what you see is status just before applying the glue.
After the epoxy has hardened – in this case about 15 minutes later – I have made final shaping and polishing of the handle. I did not go above 150 grit sandpaper though, because that would be a waste of time with this wood.
Because the used wood was extremely porous, I had to stabilize it. Marcus has already mentioned the recent fad in knifemaking that consists of infusing the wood with resin. That would be ideal here.
Well, I lack the equipment to do that. But I wanted at least somewhat stabilise the wood even so. And I wanted to use the same finish that I have used on my mother’s knife, because it has proven itself to be very resistant. So I took the boat varnish and diluted it with acetone at a ratio approximately 1:4. You can see on the picture that the undiluted varnish is a lot thicker than acetone and it has sunk to the bottom of the jam-jar. However after mixing it did not separate again for a few days by now.
For the first dip I have put the handle in the heavily diluted varnish and I waited approximately 20 minutes until no visible bubbles were rising. Ideally It would be better to do this in a vaccuum-chamber, but acetone is very good wetting agent and this should be enough for at least a few mm penetration. After that I took the handle out and cleaned any varnish from the blade immediately with acetone. Then I have let it dry in a dust-free and well heated room. All that is left now is this week each evening after returning from work giving the handle a slight polishing with 150 or 180 grit sandpaper, dipping, cleaning, leaving it dry again until I am satisfied with the surface. I am not going to measure this time exactly because it is scattered a few minutes each evening over a few days. Lets say it is 30 minutes overall, including final signing of the blade.
That makes it 1:30 or 90 minutes for all of the work described here. That also makes the knife done for the purpose of measuring the time of my actual manufacturing process, so next time we can look at the data and look what (if) can be done there to make it more efficient.