This instructable is for a method of simulating a pile of coal for modeling purposes. I designed it for my HO (1:87) scale model railroad layout, but it could be adapted to many other uses or scales pretty easily. Living in rural USA, there are odd, small, piles of coal stuck in corners, in sheds, piled by RR tracks, against sides of barns... you get the picture. It seemed like an obvious feature, but as I did some searching I couldn't find a kit for it. So as they always say, if you can't buy one (or if you don't want to)... Make your own!
Due to the fact that this must be mixed in a relatively large scale, it may be a good idea to plan to do several piles at one time.
Step 1: Supplies and Materials
-Wood char, if you don't have this, just buy the smallest bag of charcoal you can find. Don't burn something just for the procurement of this ingredient.
-A big rock. One with a roughly pyramid shape is best, but tit doesn't really matter.
-A mixing container. You will want to throw this away when your done. I use the bottom half of a fast food drink cup.
-A mixing stick, preferably long and flat so that you can mix and scoop with it.
-White glue, you want what ever type will dry as fast as chemically possible, strength isn't really important.
-Black acrylic paint, optional unless your glue doesn't dry clear.
Step 2: Crushing the Char
This part is pretty simple. Place the char in the mixing container, then take your big rock and grind (not smash) the char into a super fine black powder. The consistency in the picture shown is good for HO (1:87) scale, but if your going for any thing smaller, particularly N (1:167) then your gonna need to get a lot better than this. I usually spend 10-15 minutes for HO piles, but go by consistency, not time. You can't really go to small, and remember, this is more art than science.
Step 3: Making the Coal Mash
Now that you've got your little bowl of powder, the messy part begins. this sis the point of no return, don't say I didn't warn you, any thing you use that comes into contact with this stuff your about to make will never again be useable for any culinary or precision use again. You have been warned! Now, take your bottle of white glue and just squeeze down. This takes a lot of glue, you want it nearly 10 parts char to 7 parts glue. And... congratulations! You have just created the sticky, black, grainy mess I refer to as coal mash. if your wearing long sleeves and you haven't yet, I would roll them up. This stuff will ruin clothes.
As a side note, if you don't use dry clear glue, or you just really like that "black as coal" look, take your tube of black paint and put a good, generous squirt right in the middle. Mixing the black paint in can help counter the white glue. However the paint must be black, dark brown or dark grey won't work.
Step 4: Coal Mash Part II-The Mixing
Take your mixing stick, and mix every thing together. This isn't exactly rocket science, just mix it very thoroughly. You shouldn't be able to tell the glue and char apart.
Step 5: Piling the Coal Mash
Now just take your mixing stick (or get another if it didn't withstand the last step) and plop it down into a pile in your desired location. This is another thing that's more art than science. Just keep going in small increments until you've reached your desired size. Once your done, you may wish to give it a reduction in drying time by blasting it with a hair dryer. Just be incredibly careful not to blow it all over the place.