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Ferric Nitrate Mixing Instructions

I have 500 grams of ferric nitrate crystals. How much distilled
water do I need to mix up my etchant bath?


 I have 500 grams of ferric nitrate crystals.  How much distilled
water do I need to mix up my etchant bath? 

Hi Linda, It depends on how aggressive you want the etch to be. A
higher concentration bath will eat faster, but also lead to possible
undercutting. A less aggressive bath usually leads to a more
controlled and precise etch, but of course takes longer.

My guess is a liter of distilled water for an aggressive bath, and
two liters for a more mild bath. A little experimentation might be in
order. I mixed some up, but was only etching rings, so did a much
smaller bath in a smaller container. You don’t necessarily need to
mix all the crystals in one batch.

Better yet, someone might actually provide you (us) with specific
ratios, but I just tended to eyeball it!

All the best,
Dave Sebaste
Sebaste Studio and
Carolina Artisans’ Gallery
Charlotte, NC (USA)

Linda, I spent about 30 minutes searching for this information
because I am avoiding doing some loathsome accounting tasks. Lucky
you. I like to use Google when searching the WWW:

First though, here’s an Orchid posting by Karen Christians, who has
extensive etching experience:

I don’t know if Karen starts with ferric nitrate crystals, however.
Perhaps Karen is reading and will clarify.

The next link points to an entry on a MEMS message board; I have no
idea what MEMS is. But, the writer suggests 10 grams or less “per
liter”. Per liter of what he doesn’t say, I assume they mean per
liter of water.

And here’s a link to a table that lists metals and etchants:

If you understand what Baume is, then it probably gives a recipe.
Or, you can probably find out if you continue searching. I’ve
procrastinated long enough!

Christine in Littleton, Massachusetts, USA, which has been
transformed into a winter wonderland by a late winter dusting of snow.

I use about 4 oz. crystals per quart of distilled water. Nice .5-.75
mm etch in 3-1/2 hours with tank. Save the rest of the crystals for
adjustment or replenishment of the solution.

Baume is a method of measuring the strength of a solution, by
specific gravity I think. It looks similar to a big glass candy
thermometer, and it is suspended in the solution to measure the
strength on the scale. They can be found in places that sell photo
supply equipment like developers and fixers. I happened to special
order mine from a hardware supplier, but then I live in the middle of nowhere.

This is one of those questions where there is no real definitive

I tend to mix my ferric nitrate until it looks like very strong tea.

Per one quart of water, use 6 level tablespoons. Use only distilled
water and etch the same way I do with the ferric, which are the
little styrofoam pontoons and an aquarium pump taped outside on your
plastic container. This provides the necessary vibration which
keeps the etching process moving. You might see some crystal
buildup, ignore this and just keep etching.

It is important to make sure that what you are etching is very
clean. Grease, soap, etc., just keeps it from etching properly.

I’ll weigh out my ferric nitrate allotment and give you the oz.

Karen Christians
10 Walnut St.
Woburn, MA 01801
Fax: 781/937-3955
Accredited Jewelry Instruction