i went to a factory that produced collodion .. the addition of ether ( at least for their uses )
was the last step ... after the linens were nitrated ... they were washed / rinsed thoroughly and then
soaked in alcohol to remove the remainder of the water ... then they were dissolved in ether ...
if you buy your collodion pre-made, make sure it isn't "flexible collodion" that you can get in some of the pharmacies
( at least here in the usa ) it has camphor and other things in it that will foul-up your photographic uses ..
if you decide to make dry plates in your 35mm camera contact me, i have made some dry plate tintypes inmy 35mm camera and it is a piece of cake!