Back to Ganoksin | FAQ | Contact

Bronze patina?


#1

I have recently been casting work in manganese casting bronze. (I do
mostly one-of-a-kind work in lost wax.) I have 30 years of
experience working in sterling and 14kt.

I want to patina the bronze black. I’ve tried “Silver Black” from
Otto Frei, which contains hydrochloric acid, and also a mixture of
liver of sulfur with 10% ammonia that was recommended to me. I’ve
tried them with both coating and dipping.

Neither of them work. The patina I am looking for is similar to the
effect of liver of sulfur on sterling.

I would very much appreciate advice about this.

Thanks.
Laurie


#2

Laurie, If anyone has something for that application it would be
http://www.ganoksin.com/gnkurl/ec

Check it out. Cheers from Don in SOFL


#3

For what its worth,

I colour my bronze work as follows.

  1. Its polished to a high egree,

  2. then its de greased

  3. I use a neutral propane flame from a 2in dia burner that slow
    buning, ie, a large area of flame thats slow moving.

apply this to the item and watch the colour darken as it heats up,
do not take to a heat that glows in the dark. allow to cool.

hen burnish with a very fine brass brush to bring up the shine on
top of the dark colour.

this way, I can get a very dark brown, not tho a true black.

Bronze is better in my eyes this shade.

If you want to see this colour them advise on ganoksin and ill get
some pics uploaded.

Ted.


#4

If you are willing to get fancy with this, I can look in my copy of
Hughes’ and Rowe’s excellent book on patinas, but it’ll require
mixing up chemicals, and I’ll need to know what formula of bronze
you’re using. (ie; What the ratios of the metals are, since I’m not
a bronze sculptor so I don’t know exactly what the recipe for your
manganese bronze is) Another option is to look for it at your
largest local library - it’s “The Colouring, Bronzing, and Patination
of Metals” by Richard Hughes and Michael Rowe.

A quick look in my copy showed several nicely dark black patinas,
but I’m not sure which will have the closest effect to the liver of
sulfur on Sterling, since I haven’t gotten a chance to play with
these recipes myself yet.

Lindsay Legler,
Dreaming Dragon Designs


#5

This text referenced below is a nice table top book, but many of the
patinas do not work. For us, and we are primarily a bronze sculpture
operation, a better reference is

http://www.ganoksin.com/gnkurl/ep7z2i

The formulas work!!! One of the problems you are dealing with
(the original poster) is that the bronze alloy you are using is not
a common sculptural alloy. The manganese is the “problem”. Most
sculptural alloys used these days are either Herculoy (an alloy
containing a fair component of zinc, which makes the molten metal
pour better, but matching the welds is terrible as the zinc burns
out of the alloy very easily) and Everdure (a copper silicon alloy
which welds very well but is a bit more “difficult” to pour and get
good file, at least that is what "they"say, it is the only
alloy we use as it welds beautifully and patinas evenly as there is
no other alloying metal that burns out).

The manganese will create “problems” with patination and I am not
familiar with or have any experience dealing with such an alloy. I
would suggest that in the future, use Everdure for your castings,
then you will have a very wide variety of tested and doable patinas
on hand to color your work. Many patinas will require chemical
"mixing", but if you follow the directions/instructions, you should
not have any problems… Some patina mixes are far safer that others
and some are VERY easy to use verses others. Birchwood Casey
formulas, available from http://www.sculptnouveau.com/ is a GREAT
patina resource, located in So. California. Give them a call or e
mail them and they most likely will be able to help you thru your
patination problems.

Hope this helps. I sure do not mean to step on anyones toes with my
comments/statements. I have a number of patination references in the
foundry but my “bible” is the Kipper book. The formulas work, there
are great picture references for clients to look at. Most every
patina application will give a different result to the "previous"
application, it is just part of what make patination so
wonderful and so frustrating!!! Good luck to all who go in this
direction. You can see some of the different patinas we have done on
Cynthia’s for at http://www.ganoksin.com/gnkurl/ep7z2j

Click on the top image/text section. Any questions, shoot me
an e mail or call.

John Dach


#6
I want to patina the bronze black. I've tried "Silver Black" from
Otto Frei, which contains hydrochloric acid,....... 

I also cast bronze. I have used many alloys (most of them probably
more accurately called brass) and now use silica bronze exclusively
(also a brass) because of its casting properties and ease of working.
Black is my favorite patina color. I have used a number of recipes
for making black on bronze. I was usually disappointed. These recipes
for making black on bronze. I was usually disappointed. These days I
use a formula that is sold for gun blacking. It is made by Birchwood
Casey and contains selenium dioxide as the active agent. I think it
is equivalent to selenous acid. I have used it for bronzes up to
thirty pounds with very good results. To get a jet black color I
apply multiple coats without rinsing between as is suggested in the
directions that come with the product. If some areas do not color
well, keep applying the color agent to those spots. Sometimes it may
be necessary to lightly treat the area with steel wool.
Alternatively, I sometimes warm the object with a propane torch.

The final patina will depend upon several factors: a) the number of
coatings on the object b) the nature of of the surface prepared for
the patina (polish, cleanness, etc.) c) the final treatment of the
surface. Remember that patinating mixtures contain reactive chemicals
that attack the surfaces under treatment. As a consequence, a layer
of new colored compounds forma on the surface. These are usually not
shiney but rather of dull reflectivity. For a shining surface one
could polish it (which removes patina) or coat the surface with wax,
lacquer, polyurethane or some such. Not only does this restore the
shine, it helps preserve the treatment. Time, and exposure to the
pristine atmosphere we have to breathe (joke) will cause "evolution"
of the patina–it will not usually be stable. This is true for any
patina but the gun blue treatment is more stable than most.

Birckhwood Casey also sells a product called brass black which is, I
think, the same material as the gun blue.

I hope this works for you.
Gerald Vaughan


#7

Ted,

I would like to see the pictures of the brown color of your bronze.
If possible I would also like to see a picture of your burner and
flame.

thank you, Andy

[Edit]

How can I share files and pictures with the list?
http://www.ganoksin.com/gnkurl/ftp

Or… send the files to the attention of service@ganoksin.com and
we will upload them for you…

[/Edit]


#8

The Hughes and Rowe patination book is excellent. Got my copy when it
came out at the time I knew Michael Rowe and heard about all his
extensive experimenting. It is a “must have book”

Cheers Hamish


#9

Manganese Bronze is very high in zinc. If you go searching through
the Hughes & Rowe book, the entries on cast brass might be more
appropriate. However, here’s another thought, why don’t you copper
plate the bronze and follow that with liver of sulphur. Wrap some
steel wire around a bronze item and put it in some very blue pickle
or, alternatively you can “paint” the copper plating by dipping steel
wool in blue pickle and rubbing it on your piece.

ed


#10

I want to thank everyone for the very useful and varied
It’s going to take awhile to experiment and figure
what’s best. I’ll report in.

Best,
Laurie


#11

Have fun and the best of luck to you. So little has to “change” to
create a different patina, often difficult to figure out “what did I
do differently or what did I change” when you come up with something
different than before. Part of why I love patination work and part
why I sometimes find it frustrating, fascinating, variable, etc.

john dach


#12

Ted, I would like to see the pictures of the brown color of your
bronze. If possible I would also like to see a picture of your burner
and flame.

thank you, Andy

[Edit]
How can I share files and pictures with the list?
http://www.ganoksin.com/gnkurl/ftp

Or… send the files to the attention of service@ganoksin.com and
we will upload them for you…

[/Edit]