Back to Ganoksin | FAQ | Contact

Flux & Fire scale


#1

I have a mystery on my hands. I started working with sterling
silver in February in a class where soldering was a really difficult
issue. We used sheet solder and that liquid green flux stuff and we
were told to completely cover the pieces and solder with the flux.
We were also instructed to pre polish. Most new people (and some old
ones) were having a lot of trouble. The soldering room was a room of
grief. I did have some problems but for the most part just
considered myself lucky. Actually, doubly lucky because I hardly
ever got any fire scale at all. Now I attend a different class where
soldering is no problem. We use Dandix and the instructor tells us
to use it only on the joint areas (and the solder) where we will be
soldering and not to cover the entire piece. The torches are better
because the nozzles are smaller and there’s more control as opposed
to the larger nozzles in the previous class. Now here’s the problem,
things are sticking together just fine but I’m getting deep and ugly
fire scale. The instructor says to just bluff it off but I don’t
think this is the right solution for me because I’m using 20 gauge
sheet, the work is detailed and I don’t want to spend the amount of
time bluffing that would be required to get rid of it. I would
rather minimize the fire scale formation in the first place. I’ve
read many of the messages posted on Orchid regarding this subject and
I’m going to try using a reducing flame to minimize the oxygen and
also try Cupronil just prior to soldering as well as Dandix for the
joints/solder. Does anyone have any other suggestions? Should I be
preheating the entire piece before soldering? Should I be covering
the entire piece with Dandix if I’m not using Cupronil? Will tossing
the piece back into the pickle after I’ve exposed the layer of fire
scale through bluffing rid me of it and save detail? I have noted
that the more experienced people in the class don’t seem to have an
issue with firescale formation and they’re not doing anything to
knowingly prevent it. Is it possible that it becomes less of an
issue as your soldering skills improve? Any help would really be
appreciated. And one additional question, how does flux promote the
flow of solder and does oxygen play a role in that process?

Thanks,

Carol Salisbury
@carol_a_stella


#2

Hi Carol; You’ll get a lot of response on this, but I’m putting in my
2 cents anyway. I always completely cover any silver article I’m
soldering with Pripp’s flux. I do the same with gold articles too.
Search the Orchid archives, there are a number of recipes there, but
what I use is simply a saturate solution of boric acid in denatured
alcohol, sometimes with a minute amount of surfactant such as a drop
of dish washing detergent, but that’s not critical. The problem you
are having is twofold. You must reduce the exposure of the heated
surface to oxygen. This is accomplished by the Pripp’s flux. Second
problem, you are probably taking too long to get the article up to
temperature for the solder to flow, assuming it’s completely clean
and you’re flux is not having to overcome grease, oil, or other
contaminants at the solder joint. Pickling and rinsing before
coating with Pripp’s is a must. But keep an article hot enough for
long enough, and you’ll get fire-scale no matter how well you coat
it. What I find most people aren’t comprehending is that silver,
being a great conductor, carries heat away from the area where you
are pointing the torch, where it is dissipated by radiating off the
surface of the metal. It’s a matter of volume of heat in, volume of
heat dissipated. Sometimes it’s necessary to use a bigger torch tip,
and sometimes I’ve even had to juggle two torches on an article.
Sometimes you need to use firebricks as “heat mirrors” to maximize
the input from the torch. Sometimes it’s a matter of having the
article positioned in a way that allows you to throw heat at it from
several directions. For instance, you could be trying to solder a
large flat article on a firebrick. A lot of your heat is lost
warming up a brick. In that case, support the article so that you
can apply heat from underneath as well as from above. Having
something clamped in tweezers can sometimes cause problems as the
tweezers become a heat sink. The point is, the longer you have to
heat an article, the longer it’s in a condition where oxygen can
react with the surface, causing fire scale. How you solve the
problem is partly by experience, partly with the help of observant
instructors. And sometimes it’s a design problem. I can only point
to possibilities and encourage you to apply reason to the problem
based on what I am telling you. And what the flux does is twofold.
First, it forms a barrier to oxygen. Solder will not stick to oxides.
Secondly, being basically a borosilicate type glass when molten,
borax has the ability to take oxides into solution, so that it
dissolves them off the surface of the metal, allowing the solder to
stick. And that brings up my final point. The flux can only be
effective for so long. It gets saturated with oxides and breaks
down. So it you aren’t getting a good solder joint early on,
prolonged heating will only make matters worse. You need to stop,
pickle, rinse, re-coat and try again. And I’ve found that in such
cases, pickling doesn’t always work well enough and you need to scour
the area with pumice or some form of abrasive. Best of luck.

David L. Huffman


#3

Hi Carol and all, First, I need to mention that I manufacture one of
the anti-firescale fluxes. I hate firescale with a passion and will
do anything to rid it from all silver work.

There are several fluxes that when used properly will prevent
firescale. I will be using the word anti-fs-flux to describe any of
the commercial or home made fluxes that prevent firescale.

Firescale is formed whenever sterling is heated above about 1000
degrees F. Oxygen combines with copper to form cuprous oxide that
(**&%&^%#^%$&&())(& ) miserable stuff.

I will be mentioning ways I use to create my work. I am sure many
of our good Orchid friends have other ways to do the same things.

Let me Comment about some of the things you mentioned in your
letter.

  1. It is best to pre-polish as much of your work as you can. By
    pre-polishing you will be able to easily polish areas the may be
    difficult to polish after assembly. Soldering will become a problem
    when the residue of the polishing operation is not removed from the
    metal. The polished silver should be cleaned with wood alcohol or
    similar liquid before soldering.

  2. All surfaces, where you do not want firescale, should be coated
    with anti-fs-flux before soldering. The coating should be applied
    before each solder step.

  3. I believe that most anti-fs-flux will act as a solder flux.
    However I think there are better fluxes for soldering. I recommend
    paste flux be used for all strength requiring joints. The amount of
    paste flux used at joints should be very limited as it will flow
    away from the joint and wash away the anti-fs-flux.

  4. To properly apply anti-fs-flux heat the metal slightly. Paint
    or spray on the anti-fs-flux. If the metal temperature is correct a
    white grainy coating will form.

If you have any additional questions contact directly.

Lee Epperson


#4
 Any help would really be appreciated.  And one additional
question, how does flux promote the flow of solder and does oxygen
play a role in that process? 

Carol, these are indeed a couple of the key points.

Oxygen combines with sterling silver to cause copper oxides. It
does the same with silver solder. The oxides will prevent solder
flow, and any solder that attempts to flow over the oxides, not only
won’t want to do so, but if forced physically over them, won’t stick
properly. You NEED the flux to not only prevent oxide formation, but
to dissolve even traces of oxides that may already be there. Solder
flows properly only when both it, and the silver, are chemically
clean. Dirt, or oxides, will prevent solder flow. so thus you need
flux of some sort. Oxygen, in this case, is the enemy. fire
scale, the black scale you see right away, are surface copper oxides.
They get in the way of soldering, but will come off in the pickle.
Fire STAIN, is the oxides that penetrate into the silver leaving a
discolored and blotchy surface. These, being penetrating, are not
removed well by pickle.

Your original class, using probably batterns flux, was thus using a
flux high in boric acid, which lasts well on the metal under
elevated temps, and doesn’t burn off that quickly, so it protects
better from fire scale and fire stain than does Dandix. But it’s not
at all as active (being formulated more for gold work, which doesn’t
need as active a flux), and won’t work as well to actually remove
existing oxides and contaminants on the silver, so then it doesn’t as
actively promote solder flow. If the silver is very clean, and
you’ve got enough Batterns on the work, it will prevent fire scale
fairly well for simple (short time periods) soldering, and the solder
can flow OK. But it’s not an especially effective flux for promoting
solder flow with silver. Dandix, on the other hand, melts at a lower
temperature, and becomes MUCH more active at dissolving oxides and
various contaminants, plus because it’s a paste flux, you generally
end up with more of it on the joint. For that reason, it’s a lot
more effective at promoting solder flow. But when you did not coat
the rest of the piece, you let it oxidize deeply, and there is the
source of your fire scale. And because dandix is such a good solvent
for oxides, and it’s lower melting point, it also tends to absorb
oxygen from the air too, and somewhat quickly becomes depleted, so
even coating the work with dandix will sometimes leave you with
substantial fire scale and fire stain.

The best answer to fire scale and fire stain are simply not to let
them form. Cupronil will work, but I think an even more effective
solution is one that I mention here in Orchid every year, or more
often, when people don’t find it in the archives. Prips flux. It’s
been well documented here in Orchid (you can find my writings on it in
the archives, as well as that by others), or in the jewelry making
books, for several decades now. But you don’t usually find it in the
catalogs, so those jewelers who didn’t learn silversmithing in
college level courses (where Jack Prip first introduced the recipe,
and where it most frequently was passed on), often don’t hear of it,
or believe in it’s effectiveness, since they either aren’t using it
right, or simply haven’t heard of it. many commercial jewelers and
goldsmiths have never heard of the stuff, and many self taught smiths
are also unaware of or unfamilier with it’s use. Properly using prips
flux can be a bit of fuss and bother, but IT WORKS. The only times
I’ve ever had trouble with fire scale and fire stain were those
times when I got lazy and didn’t use the Prips flux.

The reason prips is not in the catalogs is that it’s a simple recipe
that you make yourself with boric acid, borax, and TSP, dissolved in
water. In a quart of water, dissolve 60 grams or so, of borax, and
60 grams of TSP. Add 90 grams of boric acid. You can play with
these amounts as you like. The important point is that there are two
parts each of borax and TSP to three parts of boric acid. Note that
it has to be actual TSP, trisodium phosphate, or another of the sodium
phosphates (monosodium phosphate or disodium phosphate), rather than
one of the other various cleaning agents sold in the paint
departments of hardware stores which substituted for TSP. Since TSP
is a phosphate, it can cause water pollution problems (algae growth),
which led to the marketing of the many substitutes. But in most
parts of the country, TSP is still available. Just read the labels
carefully. borax you get in the laundry aisle, labeled borateem and
sold as a detergent. Or, some of the store brand cheap detergents
are the same, for even less money. Boric acid is sometimes sold as
roach powder, or you can buy it in pharmacies or jewelery tools
supply places.

They key to using this right is to apply it with a sprayer, to metal
that you’ve already warmed up enough that the spray dries to a thin
even white crust as it hits the metal, rather than going on wet and
boiling away. You put on a thin even white crust on all surfaces of
the sterling, and THEN add just a little paste type (or other)
soldering flux to just the joints. Unless you heat the sterling WAY
too hot, the prips flux glaze that forms when it’s heated will
protect the silver from any oxidation, even through several
soldering steps if you don’t quench the piece or otherwise wash off
the flux.

The time and effort you spend applying the flux will be many times
paid back when you end up with metal that stays clean and doesn’t
require you to remove fire stain. Use the prips any time you’re
heating the metal, including annealing.

Feel free to email me if you need more details.

Peter Rowe


#5

Hi Carol, You asked some great questions. The “green stuff” was
probably something like Batterns flux or Prips flux, which will work
to prevent firescale on the surface of the piece. We use Batterns a
decent amount when fire-shaping a piece, especially – things like
granulation, drawing beads on wire, fusing, reticulating, etc.
However (and this may be overkill), I do find myself using Dandix
with it on the seams for soldering. Just seems to work better.

Firescale and firestain are always potentially an issue when working
silver. Your best bet is to prevent it as much as possible, rather
than relying on buffing to remove it – you’re also removing metal
when you buff.

I keep a tightly closed jar of denatured alcohol mixed with boric
acid on a shelf behind my soldering area. Before heating any silver,
I dip the piece into the mixture, close the jar tightly and place it
far away from soldering area, then touch the piece lightly with a
flame. The alcohol burns off, leaving an even deposit of boric acid,
which will work to reduce firescale. Then, I apply my dandix-type
flux (I’m using grifflux at the moment, but am not wedded to one
brand) to my seams and merrily solder away.

With silver, you DO have to bring the entire piece up to temp to
solder. It’s just the nature of the metal. BUT, doing it quickly and
with a larger flame will help you reduce firescale. The key is to
bring the heat up quickly and evenly, get the solder to flow, and
then get the torch away immediately. Don’t let it linger. So, yes,
practice will help you reduce the problem. And don’t be afraid to use
the larger torch tips – they will help you get there. Most
beginners make the mistake of thinking they have more control using
the smaller ones, but the problem is that they aren’t getting their
pieces hot enough to flow correctly – then they have problems with
firestain and wonder why.

Now, what do you do when you’ve gotten it? Well, pickling well and
then letting the piece sit in a bath of 50/50 pickle and hydrogen
peroxide will take care of the copper firescale (the pink stuff)
beautifully. A brass brush in the wash cycle after this treatment
will clean up anything that remains on the surface. Firestain on the
other hand (the nasty gray stuff) must be buffed off and tends to run
deep into the metal. There’s no easy fix for that one – other than
to redo the piece, sometimes! So your best bet is to keep practicing
and learn how to prevent it.

Best of luck,
Karen Goeller
@Karen_Goeller


Handcrafted and Unique Artisan Jewelry


#6

in my experience with silver, it seems like you can’t use too much
flux… as an experiment try annealing a piece of silver totally
coated in flux, dip it and heat it until it dries,you’ll notice it
will probably want to puddle up and there will be spots where there
is still no flux, especially if it has any oil on it from a mill. so
drip more flux onto the places where there is none, while still
gently heating, until the entire piece has a white crusty layer of
dried flux. this works really well for me, i haven’t had any
firescale at all since i started doing this. if you quench it hot
most of the fused flux will boil off almost instantly. for annealing
i dip it in the green flux from rio grande and then drop it into a
jar of borax/boric acid powder, take it out, and then heat the piece
while using a solder pick the smear it around evenly while it dries.
maybe that’s excessive, but it works. when soldering i do the same
thing but then after the whole piece is coated i drip green flux onto
just the solder joints, this dissloves the dried flux so you can see
the joints and also wets them so the solder bits will stick. then i
re-dry the flux on the joints, very slowly this time so the solder
bits don’t go flying from the boiling action. if i have a piece with
lots of solder bits i will put on a few, dry that spot, and then add
a few more dry that, etc. this lessens the chance of accidentally
moving one while placing the others. try it, for flux sake.


#7

I am new at working with sterling silver, started my first project
back in February. Before I took on the project I did some
self-studying (no classes, a lot of searching on the web and read a
great book) on sterling silver and my worst fear was about the fire
scale problem. From advice of others I was told that if I used the
right procedures I would not have a problem. Well everybody�s
advice was excellent (thanks everybody) and this is what I found.

For annealing I use the boric acid (roach kill) and alcohol mixture.
Cleans off real easy in a warm pickling solution and your can go
back to hammering in 10 minutes (I am working on some hollow wear
(??) and I do a lot of annealing and raising.) So far no problem
with fire scale.

For when the time comes to soldering I have been using the Prip�s
flux to coat the pieces and then a paste solder at the solder
joints. The Prip�s flux works excellently.

   The reason prips is not in the catalogs is that it's a simple
recipe that you make yourself with boric acid, borax, and TSP,
dissolved in water.   In a quart of water, dissolve 60 grams or so,
of borax, and 60 grams of TSP.  Add 90 grams of boric acid.   You
can play with these amounts as you like.  The important point is
that there are two parts each of borax and TSP to three parts of
boric acid. 

One comment on the recipe and making the Prip�s flux, the amount
mentioned makes a big batch. I break it down to a couple cups of
water and 2 tablespoons of this and 3 tablespoons of that, just as
mentioned. But where I was confused was the boiling of water. I am
not much of a cook and the first time I mixed everything together,
set it on the stove to boil and what a gooey thick mess.

So still not sure if I am making it right but it has been working
and this is what I do. Boil the water and the TSP only together.
The TSP will dissolve completely. Let the water and TSP cool down
some before adding to the boric acid and borax. Then mix the TSP
solution with the boric acid and borax.

    They key to using this right is to apply it with a sprayer, to
metal that you've already warmed up enough that the spray dries to
a thin even white crust as it hits the metal, rather than going on
wet and boiling away.  You put on a thin even white crust on all
surfaces of the sterling, and THEN add just a little paste type (or
other) soldering flux to just the joints.

Since my pieces are a little large I heat them slightly before
coating. Just warm enough that when I brush on the solution if
fizzles. Work the solution around with the brush until it coasts
completely. If it does not stick or flows off areas because of
finger oil, heat again and apply again. From by observation the TSP
will clean off the finger oil.

Using a large flame from a distance slowly heat the piece to allow
the Prip�s to dry. Using more aggressive heat, heat the piece until
the Prip�s turns a straw or golden color. Now I can let the piece
cool make any adjustments or assembly what needs to be soldered in
place. The Prip�s makes a hard coating and the pieces can be
handled or whatever needs to be done. I have soldered three or four
times on the same piece with only one application of Prip�s flux.
Believe me this stuff is great.

warren


#8
 Dandix  

Carol, I Dandix the entire piece and heat the entire piece evenly
then add just enough heat where I want to draw the solder too. You
might check your pickle, I change mine regularly so it cleans the
piece. I also use oxy/propane hoke torches for soldering. Good luck
Rich.


#9

Hi, Carol, I’m sure you’ll get many answers, and I’m not sure I have
anything different to say than others will, but here’s my take on
the soldering question.

I teach my students to always cover the whole piece with flux for
soldering, to prevent firescale, as I also do. I favor boric acid
and/or borax in alcohol. Very easy to dip, no thick mess, no boiling
to move solder around. 99% of the time, I just use that. If I’m
particularly concerned about an operation going well, I may add a
little cupronil, green flux or handiflux at the join.

As your experience grows, you learn better heat control, so you are
less likely to use too much/too little heat, and too much time to do
a joint, so firescale becomes less of an issue. But to me, it is an
unnecessary problem to expose “naked” silver to heat except in some
special circumstances, like “bringing up the fine silver” (copper
depletion).

Pickle will not really remove firescale. There’s been a lot of
discussion on this forum of the various copper oxides that can form,
and their reference names (“firescale” vs “firestain” and the like),
but to me, personally, I call anything that doesn’t come off in the
pickle firescale (which is to say, the purple/black stuff, not the
copper-colored blush). It is harder, I’m told, than sterling, so
removing it mechanically is difficult and not fun, so why let it
form? Keeping oxygen off is key. Yes, flux also helps the solder
flow. “Flux” means “flow”. Mainly, it keeps oxidation from
inhibiting the flow of the solder.

I hope I’ve addressed all your questions and that I’ve gotten it
right. This is what works for me.
–Noel


#10

Is there any new way of handling the firescale that I get when I
need to use yellow orchre? For example I cover my silver piece with
Prips flux and solder some small pieces of gold on one side. This
piece is two sided so now I must yellow ochre the previously
soldered gold pieces and turn it over and Prips the second side and
solder the gold on that side. I can’t use Prips over the ochered
side or it will “bleed” the ochre or white out and then it’s not
safe any more to assume it won’t remelt those soldered pieces. So on
this piece I get firescale on one side and also on rings that I make
when I solder a few pieces of gold on a silver ring and then rotate
it a third turn and solder more pieces on. I always yellow orchre or
white out my previous solder and can’t Prips that particular area
without bleeding the ochre. I don’t think there is a solution to
this unless something new has arrived to solve this problem. Just
thought I’d check with the experts again on this problem. Thanks!!
Annette


#11
Is there any new way of handling the firescale that I get when I
need to use yellow orchre? For example I cover my silver piece
with Prips flux and solder some small pieces of gold on one side.
This piece is two sided so now I must yellow ochre the previously
soldered gold pieces and turn it over and Prips the second side
and solder the gold on that side. I can't use Prips over the
ochered side or it will "bleed" the ochre or white out and then
it's not safe any more to assume it won't remelt those soldered
pieces. 

Unless the pieces you have soldered onto the first side of your work
are heavy enough for gravity to shift them around when the solder
liquifies you should not need to cover them with ochre…

The reason being, that those first pieces can be soldered with a
slightly higher temperature solder, and the reverse side with
slightly lower temperat ure solder. There are at least six different
temperatures of silver solder available, and perhaps close to a
hundred in the various colors and karats o f gold solders…

Another couple of factors enter into soldering on both sides of a
flat plate , for example: a sterling belt buckle with a 14KY overlaid
monogram on the front, needs to have the findings attached to the
back side. We routinely us e medium silver solder for both sides. The
monogram goes on first, and the fi ndings go on second. (The findings
in our case DO weigh enough to shift, or fall over if you have to go
back and do work on the front side - that rarely/neve r happens.)

The reason that the monogram does not shift while soldering on the
findings is because we generally support the piece in the air, so
there is no pressur e on the monogram - and most important - EACH TIME
YOU REHEAT A SOLDERED JOINT

THE SOLDER ALLOY CHANGES TO A SLIGHTLY HIGHER MELTING POINT. This
happens because some of the lower melting point metals in the solder
alloy are vapor ized, and other metals begin combining (amalgamating?)
with the “skin” between you r two pieces. Anyone who has ever tried to
remove an overlaid piece of metal s heet knows that you practically
have use a crowbar to get 'em apart! In fact I have made a flattened
"chisel" shaped tool out of titanium for precisely tha t purpose!

Another thing you might consider is your heat control. If you are
heating th e second side hot enough to get the solder to actually
"run" on the first side

  • you are probably overheating the piece. I would venture to guess
    that 90% of the really bad cases of firescale I see are caused by
    overheating…

Brian P. Marshall
Stockton Jewelry Arts


#12

Hi, Annette, Whiteout will not “bleed” once it is dry, and ochre will
not bleed if you gently heat it until it turns red-brown, then let
it air cool. Pre-heating–after drying–will not hurt with whiteout
as well. I then apply my boric acid/alcohol flux by dipping, and
proceed as usual. This works for me, I hope it does for you. I will
add, though, that if you’re working on both sides of a flat piece,
whiteout or ochre don’t really seem necessary. If the soldered piece
is lying flat on a block, even if the solder reflows, it shouldn’t
go anywhere. As for a ring, it might help to hollow out a half-round
groove in a charcoal block. Then the previously soldered pieces will
be held in place by the charcoal, and should also stay put without
ocre, unless you’re overheating. Good luck!

–Noel


#13

Annette, You shouldn’t have to use ochre on the pieces already
soldered on. Unless they protrude significantly from the surface
that they are heavy enough to fall off when you reheat the piece
they should remain in place. If not, just use a higher melting point
solder on the first appliques and lower on the next. Jerry in Kodiak


#14
This piece is two sided so now I must yellow ochre the previously
soldered gold pieces and turn it over and Prips the second side
and solder the gold on that side. I can't use Prips over the
ochered side or it will "bleed" the ochre or white out and then
it's not safe any more to assume it won't remelt those soldered
pieces. 

Annette, Yellow Ochre only prevents molten solder from flowing out
onto the ochred areas. think of it as just dirt. Solder likes
clean metal, not dirty metal, so it doesn’t flow out onto the ochred
areas. BUT. Ochre does not prevent the solder from melting at all.
Pieces soldered on, and covered with ochre, can still fall off or
shift just as easily, though the solder holding them won’t, in the
process, flow onto the ochred areas. The key to this sort of work
is simply not using an excess of solder in the first place. When a
solder joint is made, the solder at least partially diffuses into the
metal being joined, and in the process, the composition of the solder
is altered towards that of the joined metal. That both raises it’s
melting point a bit, and makes it harder to flow again. So if you
don’t over use the solder in the first place, then you should be able
to turn the sheet over and solder again, without needing ochre to
hold the previous joint in position. Try it. solder your first
pieces, and clean up any excess solder. Then try your other side,
with prips, and without any ochre. It should work just fine. You
actually only quite rarely need ochre. It’s needed when you’re doing
things like reheating the intricately mated parts of a catch or
hinge, where any slight solder flow into the mechanism would freeze
it up, or similar situations. Just to keep pieces in place that are
just soldered to the side of sheet metal isn’t what it does well,
since as I said, it doesn’t actually hold things down, nor does it
prevent the solder from melting. If the piece would fall off without
the ochre, it can fall off just as easily with it. Now, if you DO
have a situation where you need ochre, use just a little bit, as a
narrow line where you need to block solder flow, or itself flowed
into the gap you wish to keep solder out of. Exposed outer areas
rarely need it. Dry it well with a torch, even letting it slightly
discolor, and then spray on your prips right over the top. If the
metal is properly pre heated, the prips won’t go on wet, and won’t
disturb the ochre. Should work fine.

Peter


#15

Annette - Please don’t use whiteout, except for perhaps the water
soluble kind, which seems to be O due to different ingredients.

Here’s a re-post of the nasty details around what happens when you
burn whiteout - you can have a look at the article that was run in
Lapidary Journal around August of last year - they said that heating
breaks it down to phosgene gas, chlorine gas and hydrochloric acid
fumes!

Ivy

NASTY DETAILS: Phosgene and Chlorine Gases were used in WW 1 with
lethal effects - see the info heRe:
http://www.firstworldwar.com/weaponry/gas.htm Here’s an excerpt:
Following on the heels of chlorine gas came the use of phosgene.
Phosgene as a weapon was more potent than chlorine in that while the
latter was potentially deadly it caused the victim to violently
cough and choke.

Here’s where the MSDS lives:
http://www.princeton.edu/~ehs/labmanual/cheminfo/phosgene.html

As to the HCL fumes - http://www.inchem.com.ph/hcl.htm “Irritation of
the respiratory tract, with burning, choking and coughing.
Severe breathing difficulties, may occur possibly delay in onset.”


#16

Is the only way to apply flux over dried ochre or white-out by
spraying? I’ve always applied boric acid by dipping or brush, and
thus never put it over ocre etc for fear of contaminating the flux.
What kind of ‘blower’ gives an appropriate spray?

Janet


#17
What kind of 'blower' gives an appropriate spray? 

I purchased a small 3 or 4 ounce pump bottle of antipersperant at
the grocery store. It was called crystal something or other and was
alum based. Since alum is sometimes used as a pickle, it sounds
harmless. I dumped out the contents and rinsed the bottle well.
The sprayer works fine and is small enough not to clutter up my
bench.

On a related subject, my mixing of pripps flux so far has been a
disaster. Borateem is not borax but I found a box of 20 Mule Team
Borax at the grocery store. This may have been a divergence from
Peter Rowe’s method. However, I wanted to stick to the letter of
the formula. Another difference was the TSP. The label read 7%
elemental phosphorus as phosphate. I believe they meant that the
phosphorus was in the form of phosphate but “as phosphorus.” It
makes a difference in the stoichiometric calculations. According to
my calculations, TSP should be approximately 19% phosphorus as
phosphorus. No matter how you read it, the product contained some
kind of filler.

In my first attempt, I mixed everything into hot water. There was a
white precipatate that I attempted to boil to clarity. Untracht’s
book, Jewelry Concepts and Design indicates that the mixture should
be able to be boiled to clarity. I mixed a half quart into a 1000
ml beaker. The beaker gave a giant belch and blew off the ring
stand. Presto…16 ounces of white goo all over everything. 2
hours to clean up.

Second try…The boric acid and borax dissolved in hot water. In a
separate beaker, I dissolved the TSP (and whatever filler) into hot
water. Now with everything dissolved, I poured the two together.
Presto…instant white precipatate. I filtered out the precipatate
and used the resulting filtrate. It seems to work.

I plan to give it one more try. Phosphates are not very soluable in
a basic environment. I suspect that one reason the boric acid-borax
mixture is important to acidify the mixture so the phosphate will
dissolve. I plan to try adding some phosphoric acid to the next
batch (If I ever get up the gumption to do this again) to try to
ensure that the TSP dissolves. I think that phosphoric acid would
affect the balance with respect to melting point less that merely
increasing the amount of boric acid.

Supporting my hypothis is the fact that vinegar seemed to be the
only thing that would take the white precipatate off of my dark
stained woodwork. Also, Untracht’s book used disodium phosphate
instead of TSP in the formula. The third sodium is replaced by a
hydrogen in disodium phosphate. The hydrogen makes it more acidic.

If my filtrate continues to work well for me, I may just stick to
what I have…Oh well.

Howard Woods
Eagle Idaho


#18
 On a related subject, my mixing of pripps flux so far has been a
disaster.

Why make it yourself, esp. if you cannot respect the formula?
Allcraft sells it for $ 4 something. I ordered some, as I am sure
that Peter Rowe is right about it. Best, Will


#19
 Borateem is not borax but I found a box of 20 Mule Team Borax at
the grocery store.  This may have been a divergence from Peter
Rowe's method. 

Hmm. It’s been some time since I last bought the stuff. If it’s
not borax now, what is in it? When I last bought it, perhaps ten
years ago, it was borax with small amounts of whitening agents, which
were the little blue crystals occasionally seen in the stuff, which
made no apparent difference to the flux. Does the box list the
current ingredient? Of course, if you’ve got 20 mule team borax,
that’s probably purer, and that would be better. I mentioned the
borateen only because I’d used it once, and it seemed cheaper and
more widely available.

And, Re: your precipitate, It’d guess you simply didn’t buy straight
TSP. I’ve had plenty of trouble finding just plain TSP for sale, but
once found, it dissolves, though slowly, with no trouble. At least,
I’ve never had any trouble mixing the stuff up. Your descriptions of
your problems just don’t match my own. I’ve been mixing this stuff
up every few years (I make up a gallon or so at a time, which often
lasts me the next several years) since about 1973. Never had the stuff
behave as you describe. I’ve always just weighed out the chemicals,
dumped em all in a large beaker (or even just a large suacepan or soup
pot) on a hot plate or the kitchen stove, filled the beaker up with
water, let it come to a slow simmer, stirred it up now and then, and
basically let it do it’s thing till it was all dissolved. Usually
takes around fifteen minutes and several stirrings before it’s all
dissolved. Sometimes there are a few grains of something still on
the bottom of the beaker. I don’t worry about that, figuring it’s
just some insoluable filler or contminant of some sort. I pour off
the liquid into another beaker if needed, and let it cool. If some
salts precipitate back out of solution on cooling, I just add some
more water to redissolve them. This really isn’t difficult to do.

Quite frankly, I’m quite surprised at the various reports some folks
have of disasters mixing up prips flux, and I’m at a loss to
understand just what sorts of problems some of you have had
duplicating this mixing process… This isn’t, or shouldn’t be,
rocket science. All three of these salts are water soluable, even if
a bit slowly. If you’re getting weird results, recheck your
ingredients. TSP in particular is often the label put on the
substitutes. You have to be very careful with these. You pretty
much need the carboard plain carton package that says just TSP, with
no qualifiers, and which lists trisodium phosphate as the only
ingredient, unless they add tiny amounts of anti caking stuff, which
is probably OK. Many of the substitutes say things like TSP-90, or
TSP (then the word substitute in small print at the bottom), or the
like. Read the label very carefully. It will likely also have caution
statements warning that it is caustic and can cause burns or
irritation to exposed skin, or words roughly to that effect. If you
have too much trouble finding this in the hardware or paint stores,
then I’d suggest contacting a chemical supply house. Several of them
are quite good, and have been repeatedly recommended in the Orchid
list over the years for various purposes.

By the way, my first batches of prips flux were made not with TSP
(trisodium phosphate), but with monosodiun phosphate from a chemical
supply house.(It was given to me for free) It was indistinguishable,
in use and in mixing, from the mix made with TSP. So far as I know,
you can use monosodium phosphate, disodium phosphate, or trisodium
phosphate pretty interchangeably in the prips recipe. If that
impression of mine is true, then the exact phosphate concentration
needed by the flux would seem quite variable, to little ill effect
either way.

Peter Rowe


#20

Borateem is not borax but I found a box of 20 Mule Team Borax at
the grocery store. This may have been a divergence from Peter
Rowe’s method.

  Hmm.  It's been some time since I last bought the stuff.  If
it's not borax now, what is in it?  When I last bought it, perhaps
ten years ago, it was borax with small amounts of whitening agents,
which were the little blue crystals occasionally seen in the stuff,
which made no apparent difference to the flux. Does the box list
the current ingredient? 

Peter…sorry for the delayed reply…it took a couple of weeks for
me to get back to the grocery store to check the ingredients. It’s
sad what is happening to our “grocery store chemistry set.” As time
goes on it is harder and harder to find the old time products.

Borateem is now sold as a color safe bleach. Ingredients, as listed
on the box, aRe:

sodium carbonate alcohol ethoxylate (whatever that is, my Merck Index
is at my office) and sodium silicate

I have enjoyed the flux threads. Chemistry facinates me (but in the
garage from now on…I learned my lesson, no more cooking in my
"clean room.")

Howard Woods
Eagle Idaho