We get mordant questions all the time at Botanical Colors so why not create Mordant Monday??? Got mordanting questions? Email [email protected]
YOU ASKED: I’m wondering if its possible to reuse a tannin bath, perhaps by using half as much tannin powder the second time as one can do when re using a mordant bath? Recently I have made a tannin bath for linen and have lots left over, it would be great not to throw it out!
Secondly, I usually rinse the fabric after mordanting and before dyeing- is this correct?
KATHY ANSWERED: I think recharging and reusing tannin baths is a smart way to save water, energy and materials. I have heard that you can reuse a tannin bath and recharge it with approximately 50% more tannin as you have noted, and when I was in a pinch, I recharged with less than 50% and still achieved very good results. I have reused the bath multiple times with this recharge method.
The way I understand this is: If your first tannin bath used 100 grams of tannin and you have a similar weight item and you want to reuse the bath, you would recharge the bath with 50g of tannin. If the tannin bath sits for awhile (like for weeks), it may get a little moldy. In that case, I usually skim off the mold and still use the bath. If I’m concerned that the bath might be contaminated with bacteria, I’ll simmer the tannin bath to kill any mold or other microbes, then let it cool and use it. I also top off the tannin bath with water if the water level starts to drop.
It is also possible to recharge an alum bath (aluminum sulfate, aluminum potassium sulfate and aluminum acetate) with 50% more alum, and know of several dyers who reuse their mordant baths up to seven times to cut down on water use. Aluminum triformate has mordant bucket method instructions, which also saves water and energy.
As a rule, I generally rinse lightly after mordanting and before dyeing. I hope this helps!
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