The Roald Dahl of conservation physics


SGF, Supreme Grumble Framer
Feb 28, 2002
Vancouver, B.C., Canada
Grumblers often ask conservation physics type questions that I kind of know the answer to, but not in precise detail. The recent question about light is one that got me scurrying to the website of my favorite conservation scientist, Tim Padfield.

While looking at articles on light (which are very interesting but didn't quite answer the specific question that occured to me...)I started poking around in other sections.

And stumbled on "The Hunt Ball" a story about microclimates.

I think you will love it (I did) and it also addresses many questions that Grumblers have asked about microclimates inside frames, and temperature changes.

Rebecca - thanks for that! It makes me feel hopelessly outclassed but at least I get the impression that I am not the only one!

Wopuldn't you have loved to be at that unveiling of that bleeding portrait??? LOL!
I'm afraid I need that translated! I understand that the painting suffers from varying temperatures within the frame package, that depending on size fome core (insulation) and bumpons can help, but how do I use that information on a daily basis?

How can I relay that info to my customers?

Is it better for an oil painting to sit in the garage where RH fluctuates with season and temperature, or in an unheated basement where temperature fluctuates but RH can't escape?
One can observe the sort of black body heating that he saw on the Danish rail sign, when old
frames are opened. Old back mats made of bad pulp can be seen to darken where the black areas of prints or drawings covered them. Since that part
of the board would be shielded from the light,
it must be heat from IR heating of the dark media
that causes the darkening. This can also explain
why the salt ghost patterns on the glass of old
prints follows the pattern of the design.

Sorry Bob -

I was so entertained by the bleeding portrait and irate station master that I only skimmed the rest of the article.

Now that I've read it, he makes some interesting points, but it doesn't really relate so much to framing as we know it. Well, he is a scientist after all!

He is saying that rippled paper in a sealed framing system will result in microclimates within the system. When the warm framing package is hanging on a cold wall, the Relative Humidity will be higher where ever the paper touches the cold backboard. But remember, his backboard is hydrophobic styrene, not cellulose. Anyway, in his scenario, mold could grow on the low points touching the backboard.

And, in a cool room with a warm wall the opposite could happen: the RH would be higher where the paper touched the cooler glass, and so mold could grow at the high points. And you already knew this.

But in real life

1) Not many framing systems are truely sealed

2) Not many framing systems don't have a cellulose back and window mat which would prevent the rippled paper from touching either of these cooler points

The moral of the story is, I suppose, that matting serves much more than aesthetic purposes and never never sandwich paper between glass!

As far as basement vs garage, I'd go for the garage as it would be less likely to support mold growth - unless of course you created a microclimate as per above

Thanks Rebecca,

While reading the article I was trying to gain information that I could use to become a better framer. More aware of the risks and perils of "just slapping it all together".

I believe parts of the article went over my head, (think they soared WAY over my head on first read!) but on a second read I got more of the information. I can only hope that I got it right!

I definitely understand the rippling of the paper and the colder/warmer issues with the inside of the frame. WOW the aspects to consider with "microclimates" in the frame case. Explains a lot about the issues of rippled mats when customers bring their frames in to get repaired and looked at. Always good to learn something new! Thanks again.
Oy Rebecca!

Just looked at the abstract for the next article how to protect glazed pictures from climatic insult and the first thing that catches my eye is a warning not to use "insulation" (fome core?) if the piece gets direct sunlight. Well that and mounting a picture 2cm (~7/8") from the wall. That's one big bumpon!

I have a question, and sorry for frankenthreading, but does using UV glass and acid-free materials make an environment that is conducive to mold growth? I know I sound like I'm being flip again, but I am seriously curious. Any reference material you could refer me to? I'm afraid I may be getting too serious about conservation issues (art-wise)

I ask because an old wive's tale about mitigating mold is to use direct sunlight, which UV glass blocks. And if an acidic environ inhibits mold growth does a basic environ encourage it?

Is a UV/acid free microclime actually bad for prints?

Too much time on my hands, fighting the flu and my mind is working too hard, trying to justify not doing any "dangerous" work!
Molds and mildews require RH above 65%, or so to
grow and unless frames are hung on damp walls or
left in damp spaces, that is relatively rarely found in frames. The CaCO3 in the board is not likely to encourage its growth. Filtered glazing and buffered board are good and very useful, in many ways, and neither has been blamed for mold growth. Don't worry, get well.

Thanks, Hugh (on both counts!)

Maybe I'm just getting a little <strike>more</strike> delirious<strike> than usual</strike>, or letting my mind <strike>go</strike> wander.

But it has been a recurrent thought of mine, especially when I get in these beautiful old needleworks. Always have this underlying fear of unknowingly doing damage when I am trying to do what's right for the work.
Poor Bob!

That article really does make one's head spin

Again, I just skimmed, but I think he's mainly talking about outdoor framing - like dinner menu's or old fashioned paper advertising posters - with little or no matting. The conclusion is much more reassuring:

"The traditional way of mounting paper prints and watercolours can be improved by making the enclosure air tight. This is only really necessary in damp or unstable climates. The only disadvantage of an impermeable back is the risk of condensation under an extreme temperature gradient. Temperature gradients can be avoided by hanging pictures a few centimetres away from the wall and by ensuring that direct sunlight never shines upon them. Insulation behind the picture is not necessary and is a danger if direct sunlight falls on the picture, because then the glass is the coolest part and water will condense there."

These are extreme conditions he's talking about. As he says elsewhere - these are the most interesting situations to study because something exciting actually happens! Boring old we don't normally come across these situations.

Although I do recall a thread awhile back where someone's client was quite insistent about having an artwork framed for outdoor display. Too bad we didn't know about Padfield's interest in extreme environments then.

It could make a good reality TV show though - extreme framing!