filler and flux specs

as listed here:
SIF SILVER SOLDER No.43 (Cd free)

BS: 1845 AG14


CADMIUM FREE 55% Silver Solder, which is free flowing and ideal for close fitting capillary joints and for colour match on stainless.
1.5 mm diameter; melting range 630-660°C (1166-1220°F); typical composition 55% Ag, 21% Cu, 22% Zn, 2% Sn

their Cadmium-bearing No. 42 solder (42% Ag, 25% Cd) melts at a temperature about 30° F cooler and has slightly higher tensile strength.

as listed here:
Gasflux Type U white paste flux is effective from 565-870° C (1050-1600° F).

as listed here:
Wolverine Silvaloy A45 (45% Ag, 30% Cu, 25% Zn) melts between 1225° F and 1370° F.

i'm planning a trip down to the Airgas store near me for from Harris black flux (sorta cheating, this is getting frustrating), maybe some Harris 56% filler, and thin leather gloves (filler is tought to pick up with welding gloves, and i'm not yet very experienced with the torch).

as listed here, Harris Safety-Silv 56 has a different makeup than the similar Sif product: 1 percentage point more Ag, 1 pp more Cu, 5 pp less Zn, 3 pp more Sn. i could see that making a bit of difference, especially the extra tin. and i only have a couple troy oz. of Sif left because i've been globbing it on so much, so i need more anyways.
oh, the Harris spec sheet pdf lists a melting range of 1145-1205°F for Safety-Silv 56, about 20° F lower than Sif 43. will that be noticeable? i'll report soon.

3 comments:

Jim G said...

why are you going for the black flux, and why is it "cheating"?

thefastfifty said...

jim-

my remarks are based on research here, especially Hank Folson's (aka Henry James') comments here, Josh Putnam's here, and Mark Stonich's here.

thefastfifty said...

basically, black flux allows more abusive heating, both in terms of heating cycles and excessive heat. Hank says this is bad because it allows one to be more sloppy with brazing. Josh and Mark say it doesn't really have any drawbacks, and especially for the beginner can have a lot of value.