In the last big series of posts, Rainbow Reverie, I collected notes and examples about most of the the various forms of anthotype dye I've experimented with. I've figured out at least one good dye for every color except red and I feel pretty good about that. Almost as important as what substance you use to create your dyes is the method you use to extract the pigment from the original material.
There are a lot of different ways to do this and each one has its ups and downs, so I'm going to cover the most common methods. Hopefully this won't be a very long post, but it should be helpful.
Use a regular blender (not one you use for food) to puree the substance and render it down into ooze. I suggest adding either water or alcohol to dry substances (leaves, twigs, dried berries, etc) so you don't burn out your blender. Don't add too much or you'll dilute the dye, but just enough to make sure the matter in the blender is reduced to a soup. This is my default method for extracting dye because it retains all of the object, including fruit skins which often have a lot of pigment in them. It also doesn't induce any chemical changes as boiling might.
Once you've blended the base matter down to a soup, you can choose to either use that soup directly as a dye or further reduce it. Reduction will be covered as its own method of extraction below because it tends to change the final dye a good bit. Keep that in mind. For comparison purposes, blending is simply that: tossing the dye-matter into a blender, adding fluids if required and using the resulting paste/soup as a dye.
This method is only suitable for powders such as turmeric, woad, indigo, alkanet and madder extract. The idea here is that you take your powder and add alcohol or water to it in order to produce a fluid of whatever viscosity you want. The thicker the paste, the stronger your color will be. When working with powders, I find this simple method to be the best. It doesn't provoke any chemical changes, it's fast and it's simple. Why mess with a good thing?
Pay attention to your level of dilution and what you use to dilute the powder. Water will take longer to dry and give weaker colors. Alcohol dries faster and gives brighter colors, but leaves behind a lot more pigment that can collect on the surface of your paper and end up as loose dust. Trying to remove this loose dust can end up staining the whites of your paper.
I have read many guides to anthotypes that suggest boiling your dye-matter before trying to extract the color. This seems to be a hold-over from textiles procedures where heat is actually required to cause many dyes to work. This is not true for anthotypes!! The heat helps the dyes work if they need to absorb into fibers. We don't want the dye to absorb into the fibers of the paper, that makes it harder for light to break it down. Boiling seems to break down the pigment in a few organic dyes, making them duller. I have also noticed that boiled dyes take much longer to expose. This could be due to the pigment already having been degraded by the heat or some other chemical reason. I'm not sure, I'm just reporting my findings.
I Do Not Recommend Boiling. It's rarely worth the time and effort involved, but there are a few dyes that just don't work without boiling. Mostly these are going to be dyes borrowed from textiles, like madder root. In order to extract the alizarin pigment from madder roots, you have to boil the roots. I find it much easier to simply buy extracts instead of the raw plant, but if you enjoy going through the extra steps, you're welcome to.
Your method of boiling will vary based on each dye you use. The basic idea is to use as little water as possible and watch very carefully to avoid your dye boiling dry. You'll end up with a brightly-colored soup, but the liquid is much more impressive than its stain results. Please, don't judge a dye by its color.
This can be considered a Step 2, because it can be used on a dye obtained through blending, mixing or boiling. The idea here is to remove as much extra matter from the dye as possible to reduce the amount of debris or residue left from the dye-matter and get a pure liquid dye. You can use cheesecloth to filter thick pastes like blended berry or leaf mixtures but for the powder-based dyes you'll need to use something like a coffee filter to get the extra powder out of your dye. You can double-filter thicker mixtures, first using cheesecloth and then running the resulting liquid through a coffee filter for extra clarity. I've found this can be quite helpful because the cheesecloth (maybe mine is old?) lets a lot of material through.
Be aware! Filtering your dyes will make them less vibrant. They'll be very pure colors, but not very saturated. You'll get rid of all the residue and debris, but sometimes those impurities can result in some very interesting textures in the paper. I suggest filtering half of any batch of dye so you can do a side-by-side comparison and figure out if you prefer the filtered result with the unfiltered result. In a few cases (please consult Flickr for more details), filtering your dyes can change the color entirely, which is another good reason to only filter half your batch and do a side-by-side.
I think the next post will probably be about the different ways to apply your dye to a substrate and maybe touch on substrates themselves? That might be two posts. Who knows?!