Ferric Chloride what concentration and storage

kenhills

kenhills

Joined
Dec 17, 2007
Messages
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OK all you Damascus makers I have a question. I finally found some FC, bought it from a seller on ebay. I have a pound of it 98% dried granular. The question I know have is how much distilled water to mix in with it to make say a gallon? I am not at the point where i can make my own Damascus but I do like playing around with the etching and coloration of the blades I purchase. I started a thread a while back about a rose color I came up with, now I am looking for a deep gray or medium black. While I am at it how about some suggestions about storage containers for the liquid when it's mixed.
 
Here is your good rule:

Iron Perchloride Crystals
Iron Perchloride (Ferric Chloride) is dissolved in water to make Copper Etching Solution. Use equal amounts by weight of each. i.e. 1 pound of crystals added to 1 pound of water.

Now, with that in mind, you will never get a gallon with the amount you have. A gallon of FeCl/water mix, eqauling the strength of 3:1 H2O/FeCl weighs 11 pounds.
You will only want to add 1 pound of water to 1 pound of crystals, which will only give you a short quart of mix.
When you add, add the FeCl to the water, NOT the other way around.
 
Approx. 1 pint of water to each pound of FC makes a stock concentrate.
In use it is diluted 2-4 parts water to each part concentrate.

For a gallon of concentrate, , I use 5# dry FC and a gallon of distilled water ( slightly less concentrated). Add the powder to the water slow, outdoors. It will get hot, and give off chlorine.Wear safety gear....especially a face shield.

For etching, I mix one part concentrate with three parts water. I store it in the etching tank. The tank is a 18" length of 3" or 4" PVC, with a flange foot plate fitting on the bottom (solvent welded in place), and a pipe cap slipped on and off for a top.These parts are cheap at Home Depot/Lowes/etc. The base flange makes a steady stand. The cap seals snugly. The solution seems to store in the tank harmlessly. It sits outside in the smithy year round.

There are two small "V" notches on the opposite sides of the tank top lip. This is to set a piece of steel rod across to hang the blades from. Etching is much better if the blades are suspended in roughly the center, and not hung along the sides or resting on the bottom. I hang the blades on a long "S" hook made from 16 gague stainless wire.

For the best etch use a weaker solution.Remove the blade often ,clean it off, return to tank for more etching. A slow long etch done this way is more even and deeper than a shorter etch in a stronger solution. When done, wash well with soap and water rinse then neutralize with ammonia water or TSP.

You can make several tanks for different concentrations, and in different sizes.I have a tall tank for etching swords.

Cost is almost nothing; a 18" tank costs about $10 to make, and lasts forever.

Refresh the old solution with a little concentrate as it gets exhausted.

Stacy
 
If I am getting this correct 1 lb would yield 3 to 4 pints of liquid that could be used for a slow etch. Why go to a concentrate then to a diluted form. Am I missing something? Thanks for the info.
 
When you first achieve your liquid form by adding eqaul weights of water and dry particles, you have the strength of what is called 42 Baume, which is an industry grade standard. This is too strong for what we do. It needs to then be diluted some. Many of us use a 3:1 mix ratio of 3 parts distilled water and 1 part liquid 42 Baume FeCl.
Make sense?
 
Some advantags of the stock solution are:
You can make up different strength solutions for different etching requirements. Some mixes are 10:1 and others are 3:1.
The stock solution also allows refreshing the tank with a couple ounces of fresh solution as the FC gets used up.
The stock solution is always there and it is easier to store a quart of concentrate than a gallon of diluted solution.
Stacy
 
Be careful not to use too strong of a solution, or you'll etch all the layers in your damascus at the same rate(not what you want to do). Use a more diluted solution and etch your blade multiple times, with a quick rub down with a paper towel or super fine steel wool in between to remove the oxides.
 
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