Author: Chris P
Date: 2023-07-23 00:08
If they're made of stainless steel, then you can't temper them to get the colour in the same way you can temper carbon steel screws - stainless steel screws will turn a funny yellowy/pale blue colour which isn't all that nice compared to the deep blue carbon steel turns. Think of the blue colour vintage clock hands and screws are often tempered as well as the steel flat and needle springs used on clarinets.
Clean and polish the screw heads to a mirror finish, then using a blue gas flame (as opposed to a yellow flame), hold the screw using tweezers or forceps and carefully heat it up taking it in and out of the flame and watch the colour change from a straw colour (pale yellow) through to brown, then it'll turn purple and then to a deep blue colour and quench it (in oil or water) as soon as it turns blue.
If you heat it too much, it'll become a paler blue before becoming red hot which is too far. If you've overdone it, you can redo it again by papering it up and polishing it to a mirror finish and repeating the process again, only this time taking extra care to be sure you achieve the depth of blue that's desirable which is just after it's turned purple.
Cutting edges (eg. key barrel reamers and handmade taps) and burnishers require tempering to a straw colour and screwdriver tips are usually tempered blue. This is done after hardening the steel (heating to red hot and quenching in cold water or oil to harden the steel) but it's left brittle from hardening, so it will need to be tempered to take the brittleness out of the steel.
For steel screws on instruments (except stainless steel ones), it's mainly a cosmetic thing to blue steel screws and it will also go some way in preventing them from rusting. There are chemicals that will turn steel blue and you can always colour in stainless steel screw heads with a blue marker pen if you want a colour match if you want things to all look uniform.
Former oboe finisher
Howarth of London
1998 - 2010
The opinions I express are my own.
|
|
The Clarinet BBoard
.jpg){kind=small}
.jpg){kind=small}
.jpg){kind=small}
.jpg){kind=small}
.jpg){kind=small}
.jpg){kind=small}
