Disappearing and yet readable ink

?? what do you mean??

I don't understand the question either but do know that, just because you can't see any printing doesn't mean that it is not there. The human eye is quite limited in range so, if the print fades out of the range that the eye can see, it may still be visible in, say, the ultra violet region which a scanner could use.

Or possibly near infrared.

Of course, if the receipt undetectably reverts to a piece of paper = no receipt = no warranty etc.

There are special inks that flouresce when you try to copy them as a security feature. ?

Transparent magnetic-property ink, can easily be read by data-harvesting scanners.

If the ink's body is not glossy, or made to match the paper's surface (or the plastic wrapper), you won't even see it when magnified. Inks printed by a Photolitho press, are a few molecules in thickness, and are made upto molecular accuracy.

Photo-Lithography is actually so accurate in dimension, it is used for etching microchip structures.

I'm fairly sure theat Home Depot does not use this method,but one of the oldest invisible inks is URINE. When it dries, it is invisible. Just hold it up to a lamp, and the heat will turn the uremic acid brown. Now for all you spies out there, your secret is out.

...and the heat will turn the uremic acid brown...

Or, since containing some proteins, will glow in blacklight UV

We used, as kids (in the sixties... last century), lemon juice, for the process you described here, and it worked the same: Once dried, it disappears, then run hot iron over it, and it turns brown

Of course, urine is more readily available, should the occasion arise...