I finally got my hands on a (small) sample of Neo Megilp (One local art store is giving away perhaps 1/2 oz. bottles of either Neo Megilp, Galkyd, or Gamsol with the purchase of two tubes of Gamblin oil colors), and it seems to be everything it's advertised to be (as in the new Gamblin "Oil Painting Mediums" brochures in art stores): A soft, silky gel that -- at least in my LIMITED experiments -- "melts" away brushmarks and leaves an "enamel-like" finish with color glowing from within.
I can appreciate what Turner and others saw in such stuff (My favorite term is "Ruben's Jelly").
And like the thicker true gel mediums, Gamblin says (as Karin quoted) you can add up to 90% Neo Megilp to 10% paint for an impasto glaze -- you're not supposed to add anywhere near that much of any other medium to your paint (the standard advice is that the strongest paint films are pure paint, although the Old Masters used handground paints that were much more fluid than today's tube paints).
It's truly "thixotropic" -- it looks like a stiff gel (which may hurt its sales, "off the shelf"); but it liquefies upon stirring or brushing, and then sets back up when left undisturbed (Amazing!).
Over at least my small test area, the "pull" was nice, not tacky (like gloss medium, for fellow former acrylic painters); and it doesn't "puddle" like more fluid media.
David, here's an idea I just read for reducing the tackiness of Galkyd, although slowing its drying somewhat: Add 10% stand oil (but no more, to prevent wrinkling). Just an idea from that new brochure.
Neo Megilp smells about like Galkyd (which has less "bite" than Liquin, to my nose), and includes Gamsol (which is virtually odorless, as opposed to the equally safe Sansodor).
It's not yet in our Los Angeles area stores, but I understand from Gamblin it's on its way (maybe in a week or two).
By the way, when asking for it, it's pronounced "NEE-oh muh-GILP" (Don't be surprised if the sales people laugh -- tell them how it's spelled).
The information about Neo Megilp can be found on the following page of the Gamblin website...
http://www.gamblincolors.com/mediums/mediums.html
As far as I'm concerned, as long as it's from Gamblin, it should be as safe as can be for us artists and also of conservation quality, based on his alkyd resins.
And here's some information (Please see a later post) about the original megilp and maroger mediums...
http://www.jamescgroves.com/meguilp.htm
Good luck!
P.S. Hope you're feeling better, Karin (Get lots of fresh air whenever you can)!