I verified with Bob Farmer that it was okay to write about this since I got the information from a publication I purchased from him.
Anybody that likes packet tricks knows that cards wear out. No amount of 'cleanliness is next to Godliness' is going to keep the cards from yellowing on the edges or otherwise looking scruffy over time.
I don't know how many sets of "Sympathetic Cards" I've made up since I bought that back in the 1980's I guess -- but that's what got me started buying up decks with Bike faces and odd backs to make up packets.
I think it was with the purchase of Bob's "Tarodiction Toolbox" that I first read of his method of preserving packets of cards longer than normal. He told of a spray to use on the cards, and a powder to use after. At that time, I bough some of the powder and brought life back to some packets that had been used enough they handled a little rough, but I didn't get any of the spray.
Since there seems to be a recent upswing of packets, and I seem to have a never-ending need (obsession?) with making packets up out of books or videos, and since Bob released the latest version of his Headhunter with USPC gaffed cards, I decided to spring for a can of the spray.
I got it from Amazon -- it wasn't necessarily cheap, and didn't fall inside the "include it with something else and if it's over $25 you get free shipping" deal, but like all other magic-related things -- it got ordered, and truthfully it IS a large can.
I got it yesterday, and pulled out an old set of Capitulating Queens cards -- actually made this one with Queens 😉 -- I replaced a couple cards that the backs were not exactly matching colors on, and sprayed them. Following Bob's instructions, I sprayed each side 2 coats -- they dry really fast -- 5 minutes is plenty.
At that point, the cards are like they are roughed both sides, but the cards themselves feel and look just fine even though they have a protective spray applied.
I got my powder out, and applied it to the cards, shuffled them, moved them around against each other a bunch, and they work just great -- the 'roughness' all gone with the powder.
I then did a packet trick I made up from a Paul Gordon video and followed it with Bob's Headhunter cards, all three packets are just great, and according to Bob, they'll last a long longer than without the coating. Re-application of powder is easy and doesn't require the cards to be sprayed again, obviously.
Again, with Bob's blessing, here are the links for the spray, the powder, and more importantly, Bob's email address so you can write and ask him to send you information on all the awesomeness he produces -- often including great free effects!
The Spray: Use your favorite search engine for "Hahnemuhle Protective Spray for Fine Art Digital Prints" - as I said, I got mine at Amazon.
The Powder: Get it from Howard Piano at this link: https://www.howardpianoindustries.com/micro-fine-ptfe-powder/
I don't know how many cards you can spray with that can of spray but I'm thinking a lot, and that little bottle of PTFE powder is probably going to last my lifetime -- of course I AM 70, but still ... 😉
And you can reach Mr. Farmer here: firstname.lastname@example.org and follow his FB page "Bammo Magic" while you're at it.