What Step Am I Missing Here?

Maybe replace the air (oxygen) with CO2 or nitrogen.
More inert.
Also the toner/developer on the laser printer is a bad idea. The developer especially so. Nasty stuff that.

After some investigation it turns out that the compressed air I am using is not labeled to be moisture free.. The same manufacturer makes a product that is labeled moisture free. This could be my issue.

There is an MSDS provided for the case top/bottom.
http://www.amosadvantage.com/scotto...ier_cwch.asp
I am thinking of going to NGC boxes anyway, so I may go this way a little faster.

Now the toner with labels. I will have to think on this one.. The moisture in the compressed air may be the issue. Would it be any better to print labels with ink jet? I would think that any type of ink/toner would be bad..

Any others print coin labels on laser printers? Any toning issues?

Thanks for the replies already..

Possibly it is mostly what has already been stated. The air in those cans could contain moisture and you are blasting the coins with moisture. As noted almost any type of ink that requires drying must emit something in order for it to dry. Most printers have in their instruction manuals some type of statement that it is always better to allow a colored printed page to sit somewhere to dry completely.
What you may want to do is after closing your slabs, seal the edges with a clear tape. Add the lables to the outside of the slabs. Do not seal the edges with a glue since they too require the expenditure of something to allow them to harden.
Adding those moisture absorbing gel packs is a good idea but may not absorb the gasses given off from drying ink.
And remember that when you prepare all this the temperature may be much higher than the storage area. Ever notice how moisture settles out on items when going from one temperature to a different one?

If you are looking to seal the plastic holders, they are the plastic ones right.
How about "welding" the join with a soldering iron.

Close and clip the holder, then run the hot iron along the seam.

Just a suggestion.

Peter, the plastic may weld or it may be the type that just melts away. I am not too worried about trying to seal the slab, as I don't think it will ever be truely air tight. Even pcgs or ngc slabs aren't air tight.

I thought about laminating, but that would introduce a new plastic to the equation. Not sure how that would impact things. Thanks for the tips though.

I got some double sided tape to put the labels on the outside of the slab.. Will see how that works.

If they are acrylic plastic holders, they can be sealed by using acetone as a welding cement. Apply a tiny droplet with the point of a pin to the surfaces to be joined.

Experiment first! Skill is needed to do this.

Hope it all works out for the best.

For the experimenting it would definitely take some time but you could get some cheap coins of the same material as the ones you have and slab them the new way leave them for however long it took the others to tone and check them and see how theyve held up. Patience would obviously be key lol

I sprayed a '64 Kennedy in about 1966 with acrylic laqure from a spray can for an amusement. That coin is still as fresh as the day I sprayed it.

Actually, I treated three of them. The laquer tended to peel off, so I re treated just one, and put it in a Mylar 2x2, then into a PVC album page, where it remained until recently. Now in an archival quality page.