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Thanks Tony
I'll give it a try. I presume that best to use optical tissue than some paper based one (tend to break into lots of bits on long storage).
I have to take slight (but not pedantic) issue with your view that dry material is always better for long term storage. Sometimes it is, sometimes it isn't. I wouldn't keep a cecidomyiid on a pin but would keep a syrphid that way.
Generally I favour alcohol but its a case of 'horses for courses'
Dry material is very prone to damage and while I am sure that, like me, you can think of 150 year old types which are still in excellent condition; you can probably also think of many sad damaged specimens which have not stood the test of time. Basically, if you use dry material frequently for a long period, damage is more or less inevitable. Wet material is buffered against vibration damage by the viscosity of the fluid and does seem to survive well if treated sensitively (although I'll only conclude my argument in 100 years or so!). Modern containors mean that there is no reason why a vial needs to have its alcohol topped up for decades (probably 100's of years in reality) and inert plastic technology is such that exposure to air pollution, acid leachates etc is virtually nil. There is no excuse nowardays (except being poor!) for the flat-earth technology of upturning tubes in jars of alcohol etc etc (even though many current texts still groan out the neccessity of this ancient and arcane ritual.
However, my main reason for generally favouring wet preservation is that morphology is better maintained. Many dry specimens distort as they dry and I have many times, when examining a type, marvelled at the flight of fancy (or perhaps better:- educated guesswork) that enabled the original author to imagine what the thing actually looks like in life rather than what they had before them!
Just one specific example of this:- the empidid genus Monodromia Collin was characterised by having distinctly upturned antennae. They aren't actually, when seen in life or in wet material:- its just that Collin (who was an amazingly competent taxonomist) had a shrivelled up type to deal with and never saw its true morphology. I contend that were Collin have been using wet material he never would have made this bizarre error
Incidentally, I often find that if I must dry a specimen from alcohol, it can be better than dry-mounting it directly. One has to be careful that the wings etc remain open on drying. Material critical point dried from alcohol can be supurb (if brittle) but CPD equipment is expensive and not available to most.
Just some thoughts. I think we should keep open minds about preservation techniques and use which combination best serves our purpose.
Thanks again for the feedback
cheers
Adrian