I need help with a terribly stubborn black coating on a fancy
sterling silver ring that remained after I used the borax/boric
acid/alcohol mixture described in Mr. Lewton-Brain’s article here:
I followed the directions exactly but it doesn’t say how to remove
this coating. The ring has all these inaccessible parts (which is why
I was trying to protect the high polish before assembling for one
final soldering) and brass brushing won’t remove the black coating
from these areas. Brass brushing hasn’t even removed it from the
accessible areas. I don’t have an ultrasonic cleaner but if someone
out there knows that that will remove this stuff for sure, I will buy
Thank you all in advance for you advice.
I hate to make you go out and spend some money, but I would advise
you to get a simple ultrasonic cleaner. You should also look into
setting up a basic pickle pot as well. For a pickle pot, I just use a
small slow cooker ( crock pot, or what ever name it goes by ), set on
low…I got from a department store for about $15.00. I have used it
for years, and I do a very large volume of stuff. I just use a sparex
compound and it works good for both gold, and silver. The ultrasonic
is almost essential to get the still soft, and also the solidified
borax compound off your items, in a timely manor.
Jessica As a commercial gold smith I normally use a boric acid
alcohol mixture to help prevent firescale. It is removed by the
normal pickling process (I use sodium bisulfate). IF this isn’t
cleaning your pieces of the coating, and sense you don’t have an
ultrasonic I would suggest using the older cleaning process of
boiling. Mix a soap/detergent solution and place in a pan suitable
for heating then bring the mixture with your items in it to a slow
boil. DO NOT ALLOW THIS TO BOIL DRY. Remove the items, inspect and
reapply until clean. Good luck.
When your finances allow consider buying a good ultrasonic unit, and
a steam cleaner. They are well worth the expense.
Here’s a photo so anyone can see the problem.
I wonder if throwing it in a tumbler with steel shot would take the
black stuff off but still preserve (or enhance) the polish? Another
piece of equipment I’ve been meaning to buy…
Ultrisonic will most likely not clean this black residue. My
suggestion is a warm pickling solution.
Gold casting svcs.
Just to make things simpler, cold picklle works well too.
I was trained to use sulfuric acid, cold. We used baking soda in a
very saturated solution to neutralize it. Later I used Sparex in the
special Ferris pickle heater. After breaking about a dozen of these,
I started using a Crockpot. These lasted a very long time. Now, I
just use a Pyrex dish. No heat. If I really think that I need heat, I
might heat up my work and quench it. Works fine and has worked fine
for years. BTW. I get my sodium bisulfate from a pool supply. Maybe
$50 for fifty lbs. I got my last bag five or six years ago.
Bruce D. Holmgrain
JA Certified Master Benchjeweler
I just use a sparex compound and it works good for both gold, and
You might want to try Ph Minus in place of Sparex.
Ph Minus is the same chemical (sodium bisulfate) as Sparex, but
doesn’t leave the brown scum that sometimes occurs with Sparex.
Ph Minus is used to control the Ph of swimming pools & spas.
Depending on where you live, it’s available in swimming pool supply,
grocery, drug stores & home centers. The last time I bought it, a 7
pound container was about $7.00.
Try heating your ring up, and then dropping it hot, into a warm
pickle solution. This should take the dark spots off, but you will
likely have to repolish the ring. A tumbler with steel shot likely
won’t remove the spots, but make them harder to remove.
Here's a photo so anyone can see the problem.
http://www.ganoksin.com/ftp/bb.jpg I wonder if throwing it in a
tumbler with steel shot would take the black stuff off but still
preserve (or enhance) the polish? Another piece of equipment I've
been meaning to buy...
I boil work in water with SOAP, not detergent (detergent can leave a
film on diamonds) In a small dish, I use enammell one, dissolve hand
soap in hot water untill it is cloudy, boil and then add about half
a teaspoon of ammonia, clean work with a tooth brush, scrubbing and
using a jabbing action from all angles. I always have a pot of this
and clean just about every thing thats safe to go in hot water and
ammonia. You need to use it hot to help soften polish.
It sets when cold because there is so much saop in solution.
You will have to add ammonia each time you use it because it
This is an old recipe always works really well.
Ammonia degreases, is a STRONG alkali, opposite to acid, can be
equally dangerous especially industrial stuff. I use household
ammonia, not half as strong, in a well ventilated room. Always use
hand cream afterwards.
Ph Minus is the same chemical (sodium bisulfate) as Sparex,
but doesn't leave the brown scum that sometimes occurs with Sparex.
I actually have some of that Ph Minus kicking around. I am going to
give it a try. Thanks for the tip!
Thanks to all who provided so much and advice. Wayne,
your suggestion to boil the piece in detergent and water worked
great-- it got the residue off but preserved the polish. I didn’t
want to try pickling the piece (except as a last resort) because that
would have taken the polish off. Thanks also for the that
tumbling it would not have worked, that it probably would have made
it worse-- I was about to order a rotary tumbler and all the
supplies, which I can’t afford right now, and anyway polishing by
hand seems easiest to me.
Mary, I will try your cleaning and boiling process if the next ring
becomes encrusted just like the last one.
There is so much I have to learn yet!