Originally Posted by
Guaran
At level 80 flat, chances are you may not yet be optimal at mithril smelting or scalecraft to make scales. If not, go back to Cobalt for another few levels. Be sure you have done all the craft skill training quests so you have the +80 smelting passive skill, +80 stoneworking, and the +80 scalecraft. Also, if you can get a full set of t5 craft scales, triple teched will help you get to optimal on mithril several levels sooner.
Exp is faster on metal, but to really make use of this you need silos and machines near the resource fields.
So for mithril (which at level 80 you are probably not yet ready for anyway) you need ideally 4 silos, a smelter, and an anvil or scaleforge (Scaleforge best since you will get a skill boost to scalecraft). Fill 2 silos with mithril ore, 1 silo with platinum ore, then make bars, placing bars into the 4th silo. Then burn thru the bars making focus or dex scales (for Mithril only scales). You could get away with only 3 silos if you make bars then make scales alternatively. (3 silos easiest if they are of the same capacity)
Be sure you have at least one scaleform for each skill stepping. Example chest and head forms require 800 minimum skill, 1000 optimal skill (6 bars at optimal), wings and hindlegs require 900 minimum skill, 1100 optimal skill, back scale requires 950 minimum skill, 1150 optimal (guesses from memory). The point is to be sure you are using a formula you are just optimal at making to get the best exp/bar used. In making a single scale you should consume 6 bars, and get 3 back on the decon step. Net result 3 bars used for crafting+decon exp. When making/deconning at less than optimal, the exp/resource drops quickly, meaning it's a waste to do it like that. Exp/resource is calculated by making and deconning 1 scale, (craft exp + decon exp)/(bars to create - bars recovered in decon). You always want this to be as high as possible. At less than optimal (but I get more exp this way!) you might use 8 bars, only get 2 back, so 6 net bars used. And while the total exp was greater, you used double the resources when the exp gained was not double (deconning and only getting 2 bars back also yields less decon exp than if at opt). Trust the math, not a first impression. (this is a common argument with crafting newbies who swear to god that they get better exp on harder to make stuff even when not optimal)
If you do not have some silos at your disposal, then just do marble, making strength or power scales. Follow same tips given above, always craft something you are optimal at making. Since they are single resource items, you will get less exp, but can get away with just using a single stack tarbash disc, no lower bulk/higher stacks disc needed nor are any silos.