Different strains have different trichom sizes, how should one select which bags to be using for best results for a particular strain. For example, should someone who uses a 220, 160, 90, 73, 25, be usuing this for all strains, or can that person benefit from using a 40 bag in place of the 90 for strains with smaller trichomes.
Also, what is the best product by micron size for indica dominant and sativa dominant strins and what strains are better for ice water extraction than others and why? Thanks!
You're going to be catching the same stuff no matter what sizes you use; it just gets distributed a little differently depending on which bag sizes and the quality of the material you have. So this is mostly subjective and more a matter of personal preference than anything else. EG how many different grades do you want to make, and how do you want them sorted?
In general, most people use something to catch the leafy crud (most use a 220 or 190 for that), something to catch the mid stuff (you could use 160 120 or 90), and then something to catch the high grade "bubble" stuff (73, 45, or 20). I'd say you do want at least one bag less than 73, or you'll be losing some stuff you want to keep. Also note that it takes a LONG time for water to drain through the 20 bag, and some think its not worth it, since this bag catches a lot of broken trichrome stalks and the stuff may not be as good as the next bigger two sizes.
You can make it more complicated that than with more bags, but it doesn't have to be. If you're not after the purest "bubble" stuff, you could do just a 190 and a 45. The 190 to filter out the junk, and the 45 to catch all the hash.
Indica strains typically have slightly larger trichrome heads, but the general principles apply. Some think outdoor vs indoor grown stuff will have different sized trichrome heads too.
Since all resin heads become hard and break off with shearing in ice water, the technique should work with any strain. The "best" strains for making hash, are whichever ones have the flavor or other characteristics you're looking for. In general, the more resinous the strain, the more hash you'll get.