Sorry to keep asking things, but you guys are a great resource for new players! I have 2 more (unrelated) questions, and I apologize if you've seen them before.
Does your wizard's sigil only sffect your spells, or are they imprinted on items you enchant as well?
What happens to something that you changed with Muto and then made a chemical change to. For example, if you turned water into charcoal and used that charcoal to make steel, what would happen when the Muto spell ended? Or turned a stone into wood and burned it?
"The sigil also appears in the effects of enchanted devices created by the maga." (ArM5, pg 86).
Naturally, the answer to this question depends greatly upon the specific situation. In the case of the coal, any unburned coal would turn back to water, probably spoiling the forge. For the stone to wood situation, some of the ash from the fire might turn to dust at the spells termination - the magi might not even notice that!
Your wizard's sigil will also manifest from the powers enchanted into an item. Note that the item itself does not have to show those manifestations, although it is sometimes a nice touch to have it so.
It depends, discuss it with your troupe and storyguide. It also varies based on the specific situation. The sword might be perfectly normal, it might be flawed, it might be better (though I recommend against it), or it might simply show unusual appearance. A stone turned into wood and burned would... burn as wood, and when the spell expires the ashes would probably turn into sand.
In your example if you have used 'charcoal muto-d from water' to make steel, your blade will be rigid and quite prone to brake, when sword meets shield.
I would recommend to search for the tag 'ulfbrecht' or 'Secrets of the Viking sword'. Just an hour-long youtube vid , I have found it a good quick guideline to make quality swords in ARM.
Oh, I see. Thanks! My wizard's sigil is a mark that looks like a jagged scar (the scar that marks his face that he got before he was apprenticed).
What I was wondering was the viability of "Muto-ing" some stone into calamine and selling it to a local brass-smelter. Since I plan to use some of the metal produced, I don't want it falling apart after a month (plus, my mage has a sense of honor and would not want to brass-maker to suffer a bad reputation if he could help it). Tugdual's idea of it acting as a transmutation catalyst is an interesting idea, but I don't know if that was the thinking at the time. I may have to look into it.
On 2, I think it'll be an incident by incident decision but if some trace of the muto-ed material remains in the finished product, that finished product will be altered in some fashion when the substance changes back.
If that was the only source of carbon in the smelting process, I think you'd end up with some kind of especially soft iron once it shifts back. You can't have steel without carbon, and jamming the water particles in there isn't going to help. The medieval mind may not have thought in terms of carbon molecules being replaced with water ones, but they did visualize particles of hot, cold, warm, dry, etc., so a shift in that elemental composition is quite within paradigm. A preponderance of wet particles is supposed to make something more likely to change shape, and that fits a shift to softer iron.
If the muto-ed material was something more like a flux material used to help trap imperfections and remove them during the process, and charcoal does that as well as adding carbon to the mix when creating steel, then those imperfections are still successfully carried away. The resulting slag would also demonstrate some alteration upon expiry, I'm sure, but the debris won't reappear in the iron. The purer iron is nice, and would still be of increased value, but still wouldn't make a particularly great weapon.