If by melt point and flow point you mean liquidus and solidus then
yes with alloys that's true. But with pure metals such as copper,
tin, silver, gold, the liquidus and the solidus are the same
You know this, but I’ll spell it out for others that may not.
Solidus would be equivalent to the “melt point”, which means just
below this point the substance is completely solid.
The Liquidus is equivalent to the “flow point”, where the metal is a
free flowing fluid.
What you say is true, I’ll adopt the liquidus and solidus as terms
for further discussion.
I do use pure elements in jewellery manufacture, but mostly it’s
alloys, and I think most people are in the same situation (if not
totally using alloys).
The problem with vaporisation is that it does happen in 90/10
bronze, but it’s a problem that really is only really significant if
you re-melt a lot of times. The alloying of pure elements to make
bronze is dependent on when and how you add those elements.
When I make some new bronze, (which is just a mixture, not a new
element) I find that it is better to make your charge with the tin
at the bottom of the crucible, and cover with granulated fine copper.
I am using gas to do my melts, so I have to monitor the melt so that
I don’t boil the resultant alloy. This produces a nice warm bronze
alloy. I weigh my elements as precisely as I can. The smallest melt I
do is 250 grams, and currently the largest is 1.5 kg (soon to be
larger when I get my Mario working).
A friend of mine alloys his own bronze also. However, he melts in an
electric kiln (it’s a burnout oven, but it does the job), and melts
the copper first, then adds the tin.
There is a noticeable difference between our alloys.
Both methods don’t boil the copper, yet the colour variation is
Now back to helping our friend, and casting aside the colour
variation, as an issue.
Why should our friend alloy bronze, tin first?
If you melt the tin first, you will use less fuel/energy and time to
alloy your bronze. The other way around you will use more
fuel/energy and time. It does not matter whether you use gas or
radiant coil (as stated in another post I’m not sure about induction,
as I haven’t played with it).
Regards Charles A.