Image ghosting on glass

[simoonez]

When taking apart frames for reframing, there's often a sort of dusty mirror-image mark of the work on the back of the glass.

What's causing such a thing? It's normally when the image is in contact with the glass, or when it's not you can at least see where the mount had been.

[Framie]

That is exactly one of the reasons why we use a mount, keep the image off the glass or that happens.

You can see where the mount was because of fading or acid burn. Both can be reduced by using conservation mounts/UV glass.

[prospero]

It's offgassing.

Some mountboard facing papers are prone to this, usually those that use drawing papers such as Ingres. I call them sweaty mountboards. Some batches of glass also seem more prone. I may be there is a thin film of something which cleaning doesn't remove that interacts with any vapours coming from the art.

It was common practice in the past to frame pastels with the glass in contact. You will always get ghosts from these.

[pramsay13]

This was the glass from a frame I was redoing.

[Jamesnkr]

It's cool isn't it. Mostly from printed things, where the ink still has volatile elements. A watercolour wouldn't do this, I think.

[i-framer]

I read once it is actually due to salt content but off gassing sounds more feasible. Can't remember exactly where or the facts. But here here in Cairns, Australia i have seen this quite a bit.
Have seen it more i fresh prints framed same day. There is definitely a curable time on inks to paper.
Others have been from batiks, where there is a wax on the material which holds moisture or off gasses.

But it is common. nothing a framer can determine whether it will happen or not. You would need to know the age, history and medium, and the environmental conditions it will be homed in, to at least determine whether it could happen or not.

Usually, the artwork is not in contact with the art.

Another that is really common is to take a frame apart and inside the mat on the glass is frosted, this is definitely from off gassing.

[frameartnyc]

Nice glass Art you were doing. It will be complete by giving a little effort isn't it.

[Not your average framer]

A lot of older liners only touch the glass at the very edge of the glass and avoided this problem completely in most cases. These days frames with liners are not seen very much and I don't know why this should be.

Liners can be an amazing presentation and design tool and it seems a shame that liners have become just another thing of the past. Some of us, who are into handfinishing still like to offer liners when appropiate, but I think that those of us who do are rapidly becoming an endangered species.

[IFGL]

I think the Titanic gave liners a bad name, some awful framing on that film.

[Roboframer]

It will be complete by giving a little effort isn't it.

Is you Welsh? I is, look you!

[prospero]

I think the Titanic gave liners a bad name, some awful framing on that film.

Yeah but it did have a band.

[Tudor Rose]

i-framer mentions it might be due to salt content and that reminded me that I'd seen that mentioned before. Finally remembered where I'd read it.

This is what it says about it from the book "Conservation Mounting for Prints and Drawings" a manual based on current practice at the British Museum and written by Joanna Kosek.

"Gases and liquids can migrate through paper as do some water soluble solids. It is not uncommon to see examples of salt (sodium chloride) crystals migrating through paper, papyrus or parchment. On paper, papyrus and sheets of parchment which have been glazed, it is sometimes the case that salt crystals deposit themselves on the glazing above the object, causing replication of the shape of the object in the form of an opalescent bloom.

In an extreme case they may even erupt from the surface of the object. The mechanism for migration of water-soluble salts through paper involves some of the solid dissolving during a period of high Relative Humidity. This results in the material moving through the structure of the paper. During the subsequent drying period, further movement can occur as the solid concentrates at fibre surfaces at the wet/dry boundary."

(it's on page 18-19 if anyone wants to read more)