By hash do you mean hash resin made from seeds and stems or shake? If you do that is a fairly simple process of soaking a THC concentrated part of the plant in isopropyl Alchohol (they say 99% works best but I've made some pretty kick ass hash with 91%).
After soaking and shaking ur alcohol and bud, take a coffee filter and poke holes in it with a pin only a few centimeters apart from one another. Take ur filter and fasten it around the end of your container, I like to use one of those jars with the break-apart lids so at this point i can replace the metal lid plate with the filter. Now drain the alchohol through the filter (it should be dark green and thicker now) into another container. Repeat this process of soaking and draining until the alcohol no longer becomes green.
The seeds and stems or whatever bud used are now trash. I imagine if you let the bud really, really dry it might be smokeable but the effects would be minimal as the majority of the THC is now extracted into the alcohol. This is why the alcohol now needs to be evaporated out of the mixture. To do this rinse your jar of any solid waste left from your bud. Now pour the alcohol-resin mixture back into the jar, leaving the lid off. Fill a pot a little less than half full with water and set the hash jar in the water (pour out water until it sits flat in the pot if it floats). Place all of this on medium-hot heat or until the water bubble slightly as well as the alcohol.
Since 91% alcohol is extremely flamable you will need to be very careful here not to spill any on the burner. The water in the pot will keep the alcohol from heating to quickly and igniting. The water will also create a drip buffer for any alcohol that might escape the jar, even so I urge extreme cation when cooking this
Depending on how much liquid you have will determine the cooking time. I fill the jar 3 or so inches from the top and boil it for 3-5 hours. After all of the alcohol is evaporated and the mixture is completely dry you will be left with dark green (practically black) resin. The stickiness of the product seems to vary perhaps with the amout of fresh bud used but you should be able to scrape the hash with a spoon to be smoked. The final product should be dry enough to smoke directly out of any pipe and potent enough to make you forget your holding a pipe after two hits. This is great to smoke as a supplement to shwag, it increases your high quite pleasantly. I hope this helped someone. Enjoy!
