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An interesting flux technique


#1

I recently read a blog post by the very talented Orchid member Steve
Shelby

http://tinyurl.com/lhmqkb

where he mixes a flux with a very unusual component, Cabosil. It has
been several decades since I worked with Cabosil in plastic casting
and I never would have thought to mix it into flux. If you are not
familiar with Cabosil it is fumed silica. It occupies a huge volume
but weighs virtually nothing it is used as a thickener in many
products ranging from plastics to food. It is virtually inert and
does not dissolve in anything short of HF or hot molten alkalis so
when added to liquids it keeps its volume makes them into gels.

Anyway Steve’s idea was to use it to make Magic Flux into a gel to
extend it and allow it to stick to large volume forms to prevent
firescale. I thought it made for a very interesting idea so I
ordered some Cabosil.

I tried mixing it with Rio’s Stop Ox II and isopropyl alcohol in
similar fashion to Steve’s use of Magic Flux. I mixed enough Cabosil
into it to make a stiff gel and applied it as a fire coat. I felt it
worked well as a fire coat not necessarily better than others but
the way it is applied makes it a lot less messy than spraying Stop Ox
onto heated metal :slight_smile:

I tried it as a soldering flux and it was not very satisfactory but
that is not surprising as Stop Ox is not a good soldering flux. So I
tried mixing some Handy Flux with Stop Ox and then adding Cabosil
and Isopropyl alcohol agin to a some what stiff gel. I used a small
spatula to apply the flux gel almost like a caulking to the edge of
the joint. Then I pushed the solder pallions into the gel and then
heated the test piece. First off the pallions did not move while I
heated the work! I don’t know about you but keeping solder in place
while heating a wet flux is often maddening as often the steam of
the evaporating flux will launch the pallions all over the place.
These did not move it was rock solid. The addition of the Handy Flux
made the solder flow nicely across a long seam I had no voids and the
solder stayed right where it was placed while heating and very
little that flowed anywhere but into the joint. Another thing that
the gel did was allow me to place the items in it almost like a glue
they did not move at all so it acts a its own fixture if it is stiff
enough.

I think this idea has a lot of potential, I plan to continue to play
with this to try to refine the mix of components. If you like to
experiment then I would highly suggest you give this idea a try.

This the thing that makes Orchid so valuable. I never would have
thought of this and it is not the first time nor will it be the last
that I get my eyes opened by the creative minds here.

Thanks Steve,

Jim

P.S. Cabosil is finely divided silica, wear a dust mask when
handling it in its dry state and mix it with good ventilation. Also
wipe down the work area where you mix it with a sponge to clean it
up. It is not a problem once mixed with a liquid but you do not want
to breathe it. The danger of silicosis is not to be taken lightly.

James Binnion
James Binnion Metal Arts


#2

I recently read a blog post by the very talented Orchid member Steve
Shelby

http://tinyurl.com/lhmqkb

where he mixes a flux with a very unusual component, Cabosil. It has
been several decades since I worked with Cabosil in plastic casting
and I never would have thought to mix it into flux. If you are not
familiar with Cabosil it is fumed silica. It occupies a huge volume
but weighs virtually nothing it is used as a thickener in many
products ranging from plastics to food. It is virtually inert and
does not dissolve in anything short of HF or hot molten alkalis so
when added to liquids it keeps its volume makes them into gels.

Anyway Steve’s idea was to use it to make Magic Flux into a gel to
extend it and allow it to stick to large volume forms to prevent
firescale. I thought it made for a very interesting idea so I
ordered some Cabosil.

I tried mixing it with Rio’s Stop Ox II and isopropyl alcohol in
similar fashion to Steve’s use of Magic Flux. I mixed enough Cabosil
into it to make a stiff gel and applied it as a fire coat. I felt it
worked well as a fire coat not necessarily better than others but
the way it is applied makes it a lot less messy than spraying Stop Ox
onto heated metal :slight_smile:

I tried it as a soldering flux and it was not very satisfactory but
that is not surprising as Stop Ox is not a good soldering flux. So I
tried mixing some Handy Flux with Stop Ox and then adding Cabosil
and Isopropyl alcohol agin to a some what stiff gel. I used a small
spatula to apply the flux gel almost like a caulking to the edge of
the joint. Then I pushed the solder pallions into the gel and then
heated the test piece. First off the pallions did not move while I
heated the work! I don’t know about you but keeping solder in place
while heating a wet flux is often maddening as often the steam of
the evaporating flux will launch the pallions all over the place.
These did not move it was rock solid. The addition of the Handy Flux
made the solder flow nicely across a long seam I had no voids and the
solder stayed right where it was placed while heating and very
little that flowed anywhere but into the joint. Another thing that
the gel did was allow me to place the items in it almost like a glue
they did not move at all so it acts a its own fixture if it is stiff
enough.

I think this idea has a lot of potential, I plan to continue to play
with this to try to refine the mix of components. If you like to
experiment then I would highly suggest you give this idea a try.

This the thing that makes Orchid so valuable. I never would have
thought of this and it is not the first time nor will it be the last
that I get my eyes opened by the creative minds here.

Thanks Steve,

Jim

P.S. Cabosil is finely divided silica, wear a dust mask when
handling it in its dry state and mix it with good ventilation. Also
wipe down the work area where you mix it with a sponge to clean it
up. It is not a problem once mixed with a liquid but you do not want
to breathe it. The danger of silicosis is not to be taken lightly.

James Binnion
James Binnion Metal Arts


#3

Thanks for that Jim. It sounds like just the thing for large volumes
and I guess small volumes too. I hadn’t seen Dar’s post.

KPK


#4

Hi Jim,

Thanks for the post on Cabosil!
Can you suggest a place that sells Cabosil?

Dave


#5

I’m glad to see someone getting some use out of that blog post, and
then carrying the idea further to make even more interesting
discoveries. I think I have some stop-ox in my shop. When I got it I
was soldering nickel-silver, and it didn’t work well for that, but it
might work for brass, especially if mixed with cabosil.

I minimize the health hazard problem by mixing a large batch of
cabosil and water to a thick paste consistency, enough for 6 months
to a year, then when I need some, I use the paste, and only have to
handle the dry stuff once or twice a year. I think it will last
indefinitely in a paste form; there’s nothing in it to go bad.

Steve Shelby


#6
Thanks for the post on Cabosil! Can you suggest a place that sells
Cabosil? 

I bought mine from eBay as I could buy a small amount. I found lots
of sites that offered it, mostly boating sites for use as plastic
filler.

Jim
James Binnion
James Binnion Metal Arts


#7

Any store selling Epoxy in bulk will have Colloidal Silica
(Cab-O-Sil is a trade marked name) or mail order from some place
like:

“System 3” http://www.systemthree.com
"West System" http://www.westsystem.com
"Fibre Glast" http://www.fiberglast.com

Ask around someone will likely give you some, you likely do not want
/need very much, 6 ounces is a 1/2 gallon!

Mark Chapman


#8
you likely do not want need very much, 6 ounces is a 1/2 gallon! 

Sorry Mark - one of those factual things that needs to be right
(surely I won’t be alone…) There’s 128 ounces in a gallon…


#9
Sorry Mark - one of those factual things that needs to be right
(surely I won't be alone...) There's 128 ounces in a gallon... 

Mark is talking weight of a dry volume not fluid oz – that makes
his statement correct.

jesse


#10

Mark is talking weight of a dry volume not fluid oz – that makes
his statement correct.

Darn English measurements, another good reason to go metric liters
and grams not ounces and ounces.

James Binnion
James Binnion Metal Arts


#11
Sorry Mark - one of those factual things that needs to be right
(surely I won't be alone...) There's 128 ounces in a gallon... 

128 liquid ounces. Could be anything in weight, down to nothing for
a gallon of vacuum.

Al Balmer
Sun City, AZ


#12

We often see comments like, “…just google it…” If you’re looking
for a product, you might try “froogle” ing it.

www.froogle.com brings products, sources and prices, so the answer to
the question, “Do you know a source for that?” may just be froogle
it. When you do enter froogle.com, your URL will change to
froogle.google.com …that’s OK, it’s just an internal google server
thing.


#13

Colloidal silica is also used by sculptors to make ceramic shell
molds for casting bronze, etc. Most would probably part with a small
amount pretty freely, or a foundry supply could provide it in larger
quantities.

Bryan Park
www.bryanpark.net


#14

John,

You’re confusing fluid ounces with weight ounces. Two different
things. The only substance for which ounces in weight and fluid
ounces are exactly equal is water. The same as with cubic
centimeters and grams. Mark’s point is that Cabosil is lighter than
feathers.


#15
Colloidal silica is also used by sculptors to make ceramic shell
molds for casting bronze, etc. 

Ok, Cabosil is not colloidal silica, it is fumed silica even though
both are silicon dioxide they are extremely different in form.
Cabosil is a light fluffy material that takes up a huge volume for
its weight. Collidal silica is a very fine particle size silica
mixed in a liquid, the particles are so fine that they stay in
suspension rather than falling out to the bottom of the container.
Different forms different uses.

James Binnion
James Binnion Metal Arts