Encaustic is an ancient art medium that is useful for painting, collage and a few less art and more practical molding and casting applications. Encaustic medium is a combination of bleached and purified beeswax and gum damar. The gum damar is used to make the wax harder and the work more permanent.

Wikipedia has a relatively accurate entry on encaustic:
http://en.wikipedia.org/wiki/Encaustic

and an entry profiling one of the most famous/cliche early uses of encaustic. Considering the age of these, most are in incredibly good condition:
http://en.wikipedia.org/wiki/Fayum_mummy_portraits

On the last page of the instructable I have some information about using it and non-painting uses for it. So if you're not sure, skip ahead to that to see the possibilities. I'll also be posting further instructables on the subject.

This instructable is about making the medium and turning it into paint. While it's beautiful and versatile, there are a number of very important safety concerns that are included. There is a chance for serious injury while working with these materials, but all good art involves risk, so be smart and you should be fine.

Step 1: Materials and Equipment

Materials (with links to where I got some items):

- bleached beeswax pastilles http://www.danielsmith.com/products~sku~284+020+006.asp
- gum damar crystals http://www.danielsmith.com/products~sku~284+470+015.asp

- pigments
Dry powdered pigments are the way to go if you're making much of any given color. http://www.danielsmith.com/subcat~cat~800201301.asp
If you only need a small amount of any given color you can use oil paint. This isn't very efficient, though, which is why it's only smart to use it for a color you don't need much of.

Equipment:
Most of the equipment involved will have to be devoted to encaustic, because encaustic should not come in contact with anything you eat.

- an empty aluminum (soda) can
- a can opener
- a pair of pliers
- a heat source (an electric griddle is best but it is possible to do this on a stovetop)
- a mortar and pestle or other crushing method (the more crushed the damar is the faster it disolved)
- a mini-muffin tin (mine is silicone, which makes it easy to remove the wax once it's hardened) or a similar mold
You will never, ever, ever use this for food again.
- something plastic or wooden for stirring.
This will need to be okay to 400 degrees Fahrenheit. I use the handle of a plastic spoon for most stirring, and wooden popsicle stick and toothpicks for some things.
- a scale.
The one in this picture is a postal scale, and that's not right. I flaked when I took the picture. You want a kitchen type scale for this that measures in 1 gram increments.
- oven mitts, an 'ove glove' or some other way to not burn your hands
- a metal knife or palette knife.
A butter knife would do the job, but again, not the one you use for butter.

Step 2: Safety

I know you're probably prone to as much reckless abandon as I am, but please at least read this so you know how you can get hurt and can try to avoid it.

You are working with a variety of hazardous materials. Because of this there are a few things you should have to keep yourself protected:

- safety glasses
Odds are, you won't need these, but if you need them you REALLY need them. Make sure you wear them at least the first time you try this. If you manage to set your wax on fire it will behave much like a grease/oil fire. Hot wax can hit you in the face/eyes and cause severe injury. It sticks and it stays hot for a WHILE. You can also get powdered pigment in your eyes which would be especially problematic if you're making, say, CADMIUM red paint.

- breathing protection
If you can swing it, it's definitely best to work right next to an open window while you're melting the wax and damar. It's also smart to wear a dust mask at least, and a NIOSH approved mask if possible. Close the window and wear a mask for sure while working with pigments. Powdered pigments can become airborne very easily, and when this happens it is easy to inhale them. Many pigment are highly toxic, so breathing them is not a good idea.

- heat protection for your hands
I have and 'Ove Glove' and love it to death. Being a glove instead of a mitt gives me a lot more control over what I'm doing. Again, it's hot wax and it can burn you.

- baking soda
You'll use this in case of a fire. If the wax does start to burn first unplug the skillet, then remove anything flammable from nearby, then, if necessary, use the baking soda to smother the fire. If you put water on it you'll just get dangerous steam.

For the record, I've never started a fire or burned myself doing this. But there's no such things as too safe.

Step 3: Weigh Your Materials

I've made lots of encaustic medium, and my favorite ratio is 10 parts wax to 1 part damar. More damar makes for a harder wax, less damar makes it softer. You'll be able to decide on a ratio for yourself after using it for a while. I've read that it's a bad idea to go lower than 8 parts wax to 1 part damar, but I've never had trouble at that ratio, so there's probably some adjustment there.

WEIGH your wax and damar out. There's no way to do this reliably by volume (damar is a plant product and varies quite a bit). My kitchen scale cost $4 at K-Mart, and has been well worth the investment. Just make sure you use the 'tare' feature to get the most exact measurement possible. In my demo I used 50 grams of wax to 5 grams of damar. That'll give you 2 or 3 'mini muffins' worth, and that's plenty to do a smallish first painting.

Step 4: Crushing

Use the mortar and pestle to crush the damar. It leaves a residue behind, so I usually crush mine in a small plastic bag to keep my equipment clean. The more crushed it is the faster it will melt. The damar will probably have some organic matter in it, but don't worry about it now.

Step 5: Modify a Can for Melting

Use your can opener to cut the top out of your aluminum can. Use the pliers to bend the top edge to have a pouring spout. This will be where you melt and mix your ingredients.

Step 6: Melting

Place your wax in your can. Put it on the skillet and turn it to medium heat. DO NOT leave it unattended at any point from now until you're leaving it to harden.

If you're using a stove (especially a gas stove with open flame) place the can in a small saucepan with some water in it. The water helps buffer the heat and keep the wax from burning, which is an extra risk when you have open flame.

Leave your wax long enough to completely melt to a liquid. You can stir it a bit to help it along (this is where you use your mitts/glove to help not spill it. I hope that was obvious.) When it's really, really liquid add the damar.

The damar will take a while to melt (longer than the wax did). Stir it from time to time. The damar is basically tree sap, and it will turn back into a tree sap like substance part way through melting. This will probably stick to your stirrer. Just do your best to scrape it off and get it back into the wax.

When it's all COMPLETELY melted your ready for the next step. Trust me, there's no future in rushing this part.

Step 7: Pouring the Wax

Turn off your skillet/stove.

Pick up your can and pour the wax mixture into the molds. I usually fill mine about 3/4. If you spill any just leave it to set up, peel it off the surface it's on and put it back in the can to melt in next time you make medium.

This is the point where you can add some powdered pigments. Put a little in, mix it in with a popsicle stick or toothpick, then leave it alone. There is no rule about how much pigment to use because every pigment has a different intensity. If you decide later that the color is too weak you can add more pigment when you use it. If you decide it's too strong you can dilute it with uncolored medium later. I personally don't add any color at this point, but it's up to you.

Once all of your wax is out of the can and into the mold leave it alone. It'll turn white (or get lighter if it's colored) as it cools. Leave it until it's really cool and hardened up and pop it out of it's mold.

Step 8: Clean Up the Encaustic Medium

You'll notice that the bottom of each 'cake' has some debris in it. This is the organic material from the damar. There may also be some chunks of pigment. You'll want to scrape this off with the palette knife or butter knife. If your medium is uncolored and you take much wax off you can toss it back into the can to re-melt later as well. Scrape until there's no weird stuff left. As always, you're using a knife and could cut yourself. So don't.

Step 9: Using Encaustic Medium

Okay, so now you've got this, what do you DO with it?

Basically, you:

heat your medium on the skillet
paint on a rigid and porous surface (wood is good)
use natural bristle brushes to paint with it
use various metal and wood implements to drip, scrape and manipulate it
use a heat gun to remelt it on your surface
use an iron to push it around
use different colors to make images
embed paper and objects into it for collage

Outside of painting, it's a great material for model and mold related work. I've used it for casting into an existing mold, then reshaping the cast piece and making a fresh mold from it. Silicones, rubbers and resins rarely stick to it. And by rarely, I mean I've never gotten it to stick to those things, but I haven't tried every single available product. It's harder than normal wax so it doesn't melt or soften in warm weather nearly as quickly. It also stands up to mold making and casting materials that heat up from chemical reactions longer than most other waxes. It's great for some prototyping because as soon as you're done you can re-melt it for something else. It's also pretty easy to carve.