The two worst crimes against art, in respect to framing, is putting the work right next to the glass (I'll talk about that in another post) and bad hinging which I'll explain in this post.
The print above has been hinged using masking tape at the top and bottom, not only will that mean that the print can't naturally expand and contract, the tape will eventually damage the print as it has no acid-free qualities. It's also impossible to know if any of the bad stuff will remain on the print after removal. My guess is that it's unlikely every trace of 'masking tape abomination' will be gone.
Now, if you have a cheap print, that isn't particularly important, or it's one you can easily reprint then by all means stick it with whatever you like, in any way you fancy! But if it's a limited edition original work or something important you can't reprint then it needs to be hinged correctly to give the piece a chance to move around in its mount in reaction to changes in humidity and temperature.
Many people hinge artworks with pressure sensitive 'acid free' tape, and while this isn't the worst thing that could happen to an artwork or photograph, I almost always use either archival gummed paper or Japanese paper hinges with freshly made wheat starch paste. This is because both are reversible using only water. Pressure sensitive or contact tape provides a much stronger hinge, but is notoriously difficult to reverse successfully. I always look at it like this... the hinge has to be strong enough to hold, but weak enough to break!
I'd rather a customer brought a frame back because the hinge failed at some point in the future than bring back a piece where the hinge has been so strong and has stayed intact and the image/artwork has been torn or destroyed if, for instance, the frame was dropped.
This example looks better on face value as the work has been hinged at the top only. Two things are, however, wrong with this. Firstly the hinge is far too big and strong, I would mount this with two very small hinges. Secondly, I couldn't remove this tape as I feared I would damage the art, so I cut it out, left it on the art and re-hinged it. I had no idea what was in the tape so it could damage the art but, on balance, thought it better to leave it where it was rather than risk damaging through removal.
These are all examples of bad practices but the picture above was probably the worst I've seen. And it was a crime perpetrated by a 'framer'
It looked bad when I took it out of it's original frame. The tape you can see wasn't top and bottom (which would have been bad enough) but at intervals on either side. This meant that rather than the print hanging from the top of the mount the weight of it made it concertina within the mount, you can see the result below.
Unbelievably, this wasn't the worst of it. it was also taped into the mount at the top and bottom using double-sided tape... Sometimes I despair!
It's a beautiful limited edition (of 30) print that should have been treated with great respect and love, but as it is it may never completely recover from it's mistreatment. I've done the best I can for it though.