Flux

Gold Refining Forum

Help Support Gold Refining Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

denmark1982

Active member
Joined
Jan 12, 2017
Messages
36
hello again :oops:

i have a question concerning Flux

can i use ordinary Flux or what.. :) or must i buy some other Flux
 
Seriously?

Would you care to provide more details?
Without telling what you want to use it for it is like asking how many stars are out there.
 
The material you are working with will determine the flux mixture. What is you feedstock, and what are your goals with that feedstock? We will need to know all details in order to properly answer your question.

Time for more coffee.
 
denmark1982,
The question is too broad of a subject to give you an answer. Especially without you giving us any details of what you are trying to melt and what you are wanting to do chemically in that melt.
What color is a flower?

There are many different kinds of flux; many different things can be used as flux, each has a specific function, most react chemically in the melt, and are added for specific reasons.

Knowing how each cheimical (flux), metals, or minerals react in the melt can help you to decide what flux may work the best, or how to adjust the flux composition to improve the characteristic of the melt to achieve the desired result.
 
butcher said:
denmark1982,
The question is too broad of a subject to give you an answer. Especially without you giving us any details of what you are trying to melt and what you are wanting to do chemically in that melt.
What color is a flower?

There are many different kinds of flux; many different things can be used as flux, each has a specific function, most react chemically in the melt, and are added for specific reasons.

Knowing how each cheimical (flux), metals, or minerals react in the melt can help you to decide what flux may work the best, or how to adjust the flux composition to improve the characteristic of the melt to achieve the desired result.

melting gold and am using aqua regia
 
Pure gold requires no flux.

Only a thin layer of borax glazed on the dish to capture any impurities you may have missed.

After a couple times of being in solution, and proper washing and rinsing techniques, you should have no contaminants though.
 
Topher_osAUrus said:
Pure gold requires no flux. Correct!

Only a thin layer of borax glazed on the dish to capture any impurities you may have missed. If it's pure then there are no impurities to miss :) That given, if your crucible isn't holy and your gold is pure you don't need any borax at all to melt your gold.

After a couple times of being in solution, and proper washing and rinsing techniques, you should have no contaminants though.
 
Really?!?

So, I can melt in a plain ol' brand new melt dish Jon?

Fresh out the box (slowly heated up to remove moisture, of course)
I need not glaze it?

That's good to know!
Thank you sir
 
Excellent.

I have a couple dishes that I have yet to flux. Might just give that a try.

Is it a pain in the rear to get any prills to move to the main mass of metal? Or any other idiosyncrasies of the flux-less process I should be aware of?
 
Topher_osAUrus said:
Excellent.

I have a couple dishes that I have yet to flux. Might just give that a try.

Is it a pain in the rear to get any prills to move to the main mass of metal? Or any other idiosyncrasies of the flux-less process I should be aware of?
You can, but it won't flow easily and you'll lose some gold in the melt due to it sticking to the dish.

Ken
 
I haven't tried to melt gold in a "dry" melting dish. Wouldn't the gold stick to the dish without borax?

The borax also helps as a lubricant so it is easier to collect all the small droplets of gold in one big button.

Göran
 
g_axelsson said:
I haven't tried to melt gold in a "dry" melting dish. Wouldn't the gold stick to the dish without borax?

The borax also helps as a lubricant so it is easier to collect all the small droplets of gold in one big button.

Göran

Give it a go mate. Look there's no harm in using a smidge of borax but if the question is "is it required" then the answer is no for pure gold.
 
I remember from my early experiments using no borax, the gold will stick to the dish (if made of clay) if it cools down in it. If you remove the gold button with a screwdriver and some force, you will break off some clay from the dish.

Further the color of the borax will indicate many possible impurities.
 
Large melts of fine gold are done without flux for both bars and pouring shot. But small torch melts benefit from the glaze and as Solar pointed out, the added color indication helps you to determine how well you processed the gold as metal oxides of contaminants will show up in the glaze color. Rolling around molten balls of metal and having them collect into one pool is difficult without a thin glaze.
 
To clarify - concerning not needing to glaze a melting dish (as posted by Jon)

As eluded to by 4metals in this statement
Large melts of fine gold are done without flux for both bars and pouring shot.

Size of melt makes a difference as to whether or not melting in an unglazed dish can/will present a problem or not

This question came up on RPM so rather then retype my answer here - I am going to simply copy it to here

My reply on RPM -------------

For what its worth - over glazing your melting dish can/will cause the same problems as not glazing it at all - your molten gold will hang up in the thicker glaze (in other words not roll about easily in the dish) & small beads will still hang up in the thicker layer of glaze

Whether not glazed at all - or over glazed - the problem with the gold hanging up in the dish &/or small beads sticking to the dish is only really a problem if it is a small amount of gold being melted (say a half ozt or less) & that's because when the gold gets molten it doesn't have enough weight to move against the resistance of the rough surface of an unglazed dish &/or move against the resistance of a thicker over glazed dish --- in other words whether the dish is not glazed or over glazed the problem of the gold not rolling about in the dish to pick up the beads (that end up stuck in the dish) is made greater the smaller the amount of gold you are trying to melt

If you are melting say on ozt of gold or more at a time the molten gold will then have enough weight that it will roll about in an unglazed dish to pick up any & all beads that may sick to the sides --- in fact it will do so better in an unglazed dish then in an over glazed dish

So -Jon - who posted about not needing to glaze the dish (on GRF) is absolutely right in saying you don't need to glaze the dish - Jon is used to melting "at least" an ozt (& he considers that a small melt) & more often then not he is melting 3 - 5 ozt at a time --- I am sure that because Jon is used to doing "large" melts he simply did not think about how "size of melt" plays a roll in whether or not glazed or not glazed (or over glazed) effects the melt --- I will post to that thread to clarify

Bottom line - Jon is right - no need to glaze the dish "if doing larger melts"

You do still NEED to preheat &/or "slowly" heat the dish to drive out moister - or the dish will crack if you heat it to fast

Kurt
 
Even though it's possible and some people do it that way, it is recommended that you glaze a melting dish to torch melt gold. The opposite is true for graphite. Do not glaze graphite because it does not have the same properties of fused silica or clay melting dishes. Graphite is non-stick and the borax basically fouls the graphite surface. The exception is smelting in graphite crucibles.
 
I forgot to add, if you are melting by torch, there will be some contamination. Even if you start with chemically pure gold, if you melt it with a torch with a copper tip, it will have copper contamination. It may not be much but when you are talking about purity, it doesn't take much. Borax will soak up that small amount of copper contamination.
 
Geo said:
I forgot to add, if you are melting by torch, there will be some contamination. Even if you start with chemically pure gold, if you melt it with a torch with a copper tip, it will have copper contamination. It may not be much but when you are talking about purity, it doesn't take much. Borax will soak up that small amount of copper contamination.


Very astute observation.

For this reason, high purity gold that I make is melted in glassy carbon.

Lou
 
Geo said:
Even though it's possible and some people do it that way, it is recommended that you glaze a melting dish to torch melt gold.

Correct - glazing a dish has always been recommended - as it should be - especially if you are doing small melts of just a "few" grams (as already explained/discussed) --- its just not "necessary"

Jon can correct me if I am wrong - but I don't think he made his comment "as a recommendation" - he was simply making a point that it is not "necessary" --- in other words doable --- to which - being how it came up I felt the need to post a more detailed explanation of the pros & cons to melting in a glazed or unglazed dish

Keep in mind - as I pointed out - "over" glazing a dish can/will present its own problems - something rarely mentioned - people are just told to glaze their dish

The point being - Jon was/is not wrong &/or posting mis-information in "pointing out" that it is not "necessary" to glaze your dish - in fact - IMO - Jon pointing out the fact that it is not necessary to glaze a dish opened this "fact" for discussion such that it provides members the opportunity to make a decision based on their circumstance

Let me put it this way --- why would I waste the half hour or so it takes me to "properly" glaze a dish in a situation where it is not necessary

Example; - say I have a ozt or more of karat scrap I want to melt to pour shot to go to AR (assuming of course I don't already have a glazed dish handy for the job) why would I waste a half hour of my time to do this melt - when it is not necessary

IMO - telling me I "need" to glaze my dish - is in fact mis-information :!:

There is one more thing about using a unglazed dish that should be pointed out - if you are melting impure gold powders - the impurities tend to forum oxides (of the base metals) "on the surface" of your molten gold - you don't always see them while the gold is molten - but they will be clearly evident when the gold cools --- because these oxides tend to be on the surface of the molten gold - & if you are using an unglazed dish - when you roll the gold in the dish - to pick up beads - &/or when you make the pour - the gold tends to roll out from under these oxides with the oxides hanging up on the rough surface &/or on the pour spout lip of the unglazed dish - the slower you roll the gold &/or slower the pour the more likely the gold is to roll/pour out from under the oxides - leaving the oxides hung up on the rough surface of the unglazed dish --- these oxides will show up as a streak as the gold rolls out from under it - if it's a bead of pure gold that hangs up on the rough surface of the unglazed dish - it will show up as a bead instead of a streak - which can then be picked back up by bring the larger pool of molten gold back around to it

What does that mean? --- it means when melting your powders (assuming your melt is big enough to work properly in an unglazed dish) you can use the dish to "somewhat" determine if your gold is actually clean or not by doing a "slow" roll of the molten gold in the dish to see if oxides hang up on the rough surface

If so - & you are thinking ahead - you can have your water bucket for pouring shot already hand & you can decide to pour it to shot for going back to AR - rather then pouring it to a mold & ending up having to re-melt the mold pour to make shot for AR again

IMO - recommending glazing a dish should certainly stand as the "standard recommendation" --- but trying to discredit not glazing a dish as an option does not serve the purpose of this forum which is to provide information such that members can make informed decisions that best serve their circumstances

I hope between the fact that Jon brought the point to light & my efforts to explain the pros & cons has served that purpose

Kurt
 
Back
Top