Texas Instruments TI59 weird card problems

[Ren]

(11-01-2021 01:10 AM)voltaage Wrote:  Also I had to remove the varnish of the sheets and sand them a little bit

Many alumin[i]um cans have a plastic coating inside.
An acquaintance of mine, to illustrate that point, will put an unopened beer can into a bowl of Hydrochloric (?) Acid to about midway up the can. After a while he lifts the can out to reveal the alumin[i]um portion of the can that was in the acid has dissolved, but the beer is still contained in the plastic that remains.