1. Put two cups of water in a sauce pan and bring it to a simmer, then add 1 cup of mashed potato flakes (I got the cheapest plain stuff at HyVee). Stir constantly until smooth - about 3-5 minutes - then add 1 Tbsp liquid starch and 1/3 or 1/2 cup water, stir until smooth. Then take it off the heat and allow it to cool. I kept it overnight in the refrigerator so it would not mold.
2. (You may skip this step if you already keep some print paste on hand.) To make print paste (what you mix the dye into), mix 9 Tbsp urea in 1 quart warm water. Separately, mix about 5 Tbsp sodium alginate with enough rubbing alcohol to make it look like wet sand. Gradually mix the sodium alginate & alcohol into the urea-water. This works best with a mixer, but it's not impossible without it. It will thicken as it sets up. (The alcohol helps to keep it from molding. It is recommended to keep it in a refrigerator, but I have left mine out for over a year now and it's still fine.) I am suggesting this step now because that will give it time to thicken before you need it.
3. Stretch out your PFD fabric on your print surface.
4. Spread the potato-starch over your fabric, not going all the way to the edges, but covering the whole surface. At this point, it is up to you to decide where to make areas thicker than others, or to draw other spaces into the potato where the dye will penetrate. Next, you leave the potato to dry completely. A fan helps, and the faster it dries, the less it will mold. But even if it molds, it's not a big deal.
5. Once the potato is dry, it will have a crackle texture. If you want more crackle, roll or crumple it up and then re-stretch it back onto your printing surface. Mix your dye and print paste. I used 2 tsp dye powder (Midnight Blue) in about 1/8 cup of water, then mixed it with about 1 cup print paste (you will feel like you are mixing and mixing and nothing is happening until "poof" you made it to the magic moment).
6. Mix in your soda-ash activator (you do not need to do this if you pre-soaked your fabric in soda ash). About 1 tsp soda-ash and a little bit of water can then be mixed into the dye-paste. Know that the moment the two mix, the dye is activated and will gradually get weaker, so be prepared to use it after you once again meet that magic moment. I don't like it to be too thick at this point, so might add some water so that it spreads easier, but there's a fine line since you don't want it to be too runny either.
7. Spread the activated dye paste over the dried-potato-covered fabric until it is about even all over. As you spread, the potato will soften and be able to detach, so be careful as you are spreading. You can cover the fabric then with some saran wrap and let it sit, or simply let it dry. Realistically, it probably doesn't need to sit for more than an hour, but I usually leave all my dyes to sit for about 24 hours anyway.
8. Set your fabric in a bucket of water and allow the potato to dissolve off. (I usually dump this in the toilet rather than putting it down the drain.)
WARNING:
Make sure to follow precautions when using dye and other chemicals. For powder chemicals, always work in a well-ventilated area, wearing a dust mask and gloves. When working with liquid chemicals, wear rubber gloves (this includes the rinsing process).
Other Notes:
Fabrics that work best for this process are cottons. Silk will work, but you do not want to pre-soak it in soda-ash because bases will break down the silk fibers. For initial tests, I like to use inexpensive unfinished muslin (dyer's cloth if you get it from JoAnn). If you want to use fabrics with a finish (permanent press, sizing), you will need to cook it in muratic acid to remove those finishes (this is a toxic process requiring great ventilation, a cooking space not used for food, and good chemical gloves).
These notes were specifically written for using instant mashed potatoes, but you will get different results using other products, like potato dextrin, which you can get from DharmaTrading or ProChemical & Dye. I used the dextrin before trying the mashed potatoes, and the main difference in the process is that in step one, you simply boil a cup of water, add 1 and 1/3 cup dextrin powder and mix. No starch and no cooking of the powder mixture is necessary. Here are images of the results using dextin instead of instant potatoes:
All images copyright Katrina Boles
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