With our 500T - Temp is about 185 - Time is 20 to 60 seconds - We also use the special coversheet so the gloss surface of the photo doesn't become matte. Caution - be very, very careful if it is a older Cibachrome print (made by Ilford) they are very difficult to mount and it is very easy to have the emulsion "bubble" - If you can, test a corner of the print before you commit to dry mounting the entire piece.
With the Vacuum heat press we use the minimum recommended bonding temperature for whichever dry mount film/tissue we are using. Sometimes DryTac, othertimes Seal/Hunt. Usually dwell 5-6 minutes, depending on substrate. Will boost temp about 5 degrees if not bonding. Cool prints under 1/4 plate glass.
We mostly mount to 4-ply rag with as slick a finish as we can find. I don't drymount Ilfachromes...way too many things can go wrong, and they have no sense of humor.
After the surface of first Cibachrome (Ilfochrome) we dry mounted resulted in the dreaded and well documented "orange peel", we turned to PMA. Cibachrome does not react to heat at all well. And, because of the incredibly smooth surface of the Ciba material, we don't believe that lowering the heat or shortening the dwell time in the press will result in any kind of good bond with the substrate.
PMA is, of course, a messier procedure, but a whole lot more forgiving than trying to dry mount it.
Having dry mounted with every conceivable substrate/adhesive combination, there is simply no better way to go. (Unfortunately, I've done hundreds) And if it is a high gloss Ilfordchrome classic--every little bump shines through--NOT an attractive look.
The static holds securely and the plexi gives the sleekest surface reflection. No heat, no sticky stuff, no mess.
(ADDED BONUS: I personally love the fact that I can later take the photo OUT of the framing package and slip it into a portfolio,if need be.)
Barb is right about the static mount, although the static charge may dissipate in humid conditions.
As a precaution, I usually use 1/4" acrylic, which has more static charge than thinner plastic, a brand with paper masking (not peel-off plastic). I remove the masking paper only where the photo will reside, leaving a perfect "sinkmount" of masking paper, to help in case the static charge gives out.
The masking paper and its adhesive are not chemically suitable for most items framed, but the plastic photo doesn't mind, I'm told.