Dangers of humidity: A real-world case

[FramerDave]

In early May I moved and of course had to re-hang every picture I own. In the bedroom are thee reproductions of Dürer's three masterworks, Melencholia, St. Jerome in His Study and Knight, Death and the Devil. Obviously not originals, but nicely done on heavy rag paper and some of my favorites.

They were all framed about nine or so years ago. Conservation quality mats, fillet isolated with a 4-ply barrier, UV-filtering glazing, hinged to a 4-ply mat, the whole treatment. Only thing I would have done differently would have been to use plastic coated wire instead of braided wire and used anything but the brown Kraft paper. But that's all that was available to me at the time.

This morning I happened to notice that one was badly rippled, worse than it's ever been. I've accepted that they have a life and will move a bit according to the conditions, but this was bad. Heavy horizontal ripples across it and if it had been much worse it could have contacted the glass.

Then the light went on. It was hanging on an outside wall. In Houston, with 99% humidity and rain almost every day for the last week. I took it down immediately and saw that the dust cover looked even worse than the art. The most alarming part were the wet-looking spots on the wall. I don't think mold had started yet, but it could have started soon. On top of that there were a number of tiny insects crawling around there. Fortunately none of them had eaten through the dust cover and set up home. I think.

So I plan to remove the dust cover and remove the contents of the frame. I'll toss the backing (probably AF foamcore) and allow the art/mat package to dry out before I refit with a Coroplast backing, sealed to the frame with Lineco's frame sealing tape. I just wish I had some Tyvek. I've also implicated the bumpers. They're flat disk-shaped ones, rather than the domed ones I prefer. They didn't hold the frame away from the wall enough to allow for good air circulation.

I hope this takes care of it. Only other thing I can think of would be to seal it all with Marvaseal, but I can't bring myself to buy a roll of it just for a couple frames. I'm planning to wipe the wall with alcohol in order to (I hope) kill any mold spores. Thoughts?

So boys and girls, let this be a lesson. When you're warned about outside walls, basements and bathrooms, pay attention.

It could happen to you.

 

[Jim Miller]

That frame may be an expensive hygrometer.

Yup, that's moisture, alright.

Dave, you probably should have a closer look at that wall. With so much moisture penetrating to the interior, the outside surface may have been violated and the inside of the wall might be a moldy mess.

Yes, Marvelseal is marvelous, but you can cover the back of your frame with clear film or Coroplast, and seal it with Lineco metal-backed tape, or other not-so-porous materials.

In any case, a generous air space between that wall and whatever hangs on it seems like a good idea.

 

[Val]

I'm planning to wipe the wall with alcohol in order to (I hope) kill any mold spores. Thoughts?

It could happen to you.

Up in the Northern California Redwoods where I used to live, that was a huge problem. Part of our spring cleaning routine was always scraping the winter's mold off the walls. ACK! And we learned the hard way, like your situation, Dave, about not hanging important art on an outside wall.

Rather than alcohol, I would suggest a bleach/water solution to wipe the walls. Or if you feel like repainting, a primer of some stuff called Kilz, that has an anit-fungal property in the paint.

Makes me glad I live in the high desert....dry, dry, dry.

 

[j Paul]

Tyvek Hunt.

See if there is any construction going on around you. Stop and ask when you see workers, probably have scraps of Tyvek from window and door opening that you can have for free, if you don't mind the logo's probably printed on it.

 

[PaulSF]

Wiping the wall seems like a real waste of alcohol.

 

[wpfay]

Welcome to my world...email me & I'll send you a small quantity of Tyvek...it won't help, but you'll feel better.

 

[Jay H]

There was one wall in my wife's restaurant where like 5 frames became totally soaked. I'm not sure how becuase there was no leak on the wall. The frames were just WET. They had mold and mildew and tiny white wormy things. It was so gross. I carried the frame outside to take it apart.

That was about a year ago and everything is fine with those pictures so far. I have no idea what happened with this one wall but something went wrong. The mold hasn't returned yet either.

Now these frames were nailed flush with the wall. Like Jim suggests, I wonder if you had more distance between the wall and frame, if that would help?

Carry on.

 

[FramerDave]

Just an update...

I took it off the wall and left it to dry out. Within a few hours the dust cover had shrunk back tight, hardly a ripple. I took it off today to check out the backing, which still felt a tiny bit cool and damp, so I'll let it all dry out.

I'm going to stick with the Coroplast and frame sealing tape plan. That and better bumpons to provide for more airflow behind it should do the trick. Thanks for the offer of the Tyvek, but I think with the Coroplast it would be overkill.

I'll keep an eye on it and if things get bad again I may just hang a piece of decorative art there instead.

And Paul, wiping the wall was not a waste of alcohol. Domestic beer is.

 

[JohnR]

Are these masonry walls? Do you have airconditioning? Sounds like you have a moisture problem that needs fixed before hanging any favorite art on the walls.
John

 

[FramerDave]

Are these masonry walls? Do you have airconditioning? Sounds like you have a moisture problem that needs fixed before hanging any favorite art on the walls.
John

Seriously? I wouldn't come within 500 miles of Houston without AC.

The wall it was hanging on is at a corner, so it's somewhat protected. There's also a large oak tree pretty close by. So these conditions, along with all the rain lately, keep the area pretty humid. Combine that with maybe a failed vapor barrier and you see what you get.

I'm going to take a closer look. Oh, the walls are the usual lumber/plywood/drywall.

 

[Bogframe]

Dehumidifiers and dessicant silicagel sound like they could be your best friends, but I agree with Jim on this one. I think you're going to have to open up that wall.

 

[Jim Miller]

There are different kinds of desiccants, but to my limited knowledge, they all work basically the same way. Here's my understanding...

Desiccants are great for regulating moisture content when the environment is generally favorable, but may suffer occasional spikes of high or low humidity. Preconditioned to a specific level of humidity, it will try to regulate its closed environment to that level. If the air inside the enclosure is wetter, it will absorb moisture exceeding its conditioning. If it is drier, it will release moisture.

Given that purpose, when a desiccant is placed in an environment that is usually wetter than desired, it can recondition itself to the higher moisture content over time. That is, it will absorb moisture until it can't absorb any more, and then it will try to regulate its environment to the higher humidity level if/when the ambient humidity drops. That would be not good.

I would use desiccants only in frames that are sure to be in stable, desirable environments most of the time. I can't remember the last time I put a desiccant in a frame, but if I ever do it again, I probably will put a label on the back recommending that the desiccant be reconditioned annually. Reconditioning may not be necessary, but if there is enough concern about the ambient conditions that a desiccant is installed in the first place, then it should be checked to make sure it isn't doing more harm than good.

Am I missing something here?

 

[preservator]

To elaborate on what Jim has said, climate buffering materials (silica gel,
wood, cotton, etc.) are simply sponges. They will take up or give up moisture
depending on their surroundings. When we think of them as dessicants, we
may imagine them only in their role as absorbers and forget that they work
both way. They are only useful in enclosures that are not completely sealed.
If the package has a vapor barrier seal, matting materials are likely to succeed
in modifying its conditions as temperature changes. If the package in poorly
sealed, the climate buffer can become too wet or dry. If the package is mostly sealed, the added climate buffer will protect its initial conditioning
as conditions change, without. These materials will only function properly,
when surround conditions vary. If the environment is too wet or dry, and the
package leaks, its interior will wet up or dry out and the climate buffers will
help maintain those dangerous conditions.


Hugh

 

[Bandsaw]

I live in a rain forest on an island off the west coast of Canada.

The bad part of living here is that it rains - often.

The good part of living here is that it rains - doesn't snow - no droughts, always green and lush.

And some sun almost every day.

Just the way I like it.

Now these soggy frames - if you seal it it will take longer for the humidity to get in.

But it will also take longer for the humidity to get out.

The cycle of humidity rising and humidity dropping must be allowed to happen.

Humidity is water vapour - water as a gas and part of the air. This water vapour has a partial pressure as part of the air and if the humidity outside the frame goes down and its partial pressure goes down the water vapour pressure in the frame will cause some of the humidity to move out of the frame. The frame must allow this to happen. If this doesn't happen and the humidity in the frame stays high and there is a temperature drop the air will pass water vapour saturation and there will be liquid water in the frame. And there will be mold in the frame soon.

Ventilation is the answer for the frames and the wall.

The inside of the wall should have a vapour barrier but from there out the wall should breath well - I assure you we know. Due to some politics our building codes were changed a few years back on the advise of some experts (an expert is a guy with a briefcase more than 500 miles from home) with disastrous results.

PS - One of our famous artists suggests using wine corks as bumpons between the frame and wall. He suggests cutting them in half and using them to keep the frame an inch from the wall.

Lemesee - that's 2 bottles per frame.

 

[Jim Miller]

...Now these soggy frames - if you seal it it will take longer for the humidity to get in.

But it will also take longer for the humidity to get out.

The cycle of humidity rising and humidity dropping must be allowed to happen....If this doesn't happen and the humidity in the frame stays high and there is a temperature drop the air will pass water vapour saturation and there will be liquid water in the frame. And there will be mold in the frame soon.

Ventilation is the answer for the frames and the wall...

What you say makes sense, but ventilation isn't always the right answer, and sealing a frame can be a good strategy. We may be talking about different definitions of "seal" in framing.

One purpose of a tightly closed frame is to slow the rate of change on the inside of it, in response to ambient changes on the outside of it. Slowing the rate of change reduces expansion/contraction stress on the fibers of things hygroscopic, and generally reduces the high and low extremes of temperature and humidity inside the enclosure. That involves filler boards and a tight dustcover, but it is not a sealed frame.

For display in ambient conditions generally comfortable to people, such as a climate-controlled building, tightly closing a frame is the best strategy because, as you pointed out, the frame can slowly adapt to its surrounding conditions. Average temperature would be about 70 degrees F, and relative humidity would be about 50%. Variations of 25% up or down might be common, with occasional, short term extremes of 50% either way.

The problem you describe could happen if uncomfortably high ambient humidity were the normal condition. In tropical and very wet climates, such as you described, that certainly could be a problem. In high ambient humidity, if slowing the rate of expansion/contraction cycles is not a concern in the framing, then ventilation may be best.

On the other hand, if preserving the item framed is a concern, then slowing the rate of change inside the frame would still be beneficial. In ambient conditions of extreme humidity, such as you described, a completely sealed frame could be a better strategy than opening it up. By Hugh Phibbs' methods, a frame could actually be made submersible, and that would be a completely sealed frame. But in order for that to work, all of the hygroscopic materials must be pre-conditioned to a low moisture content, and the intergrity of the seals must be checked regularly. If humidity inside the sealed frame were above, say, 20%, then mold & mildew could be a problem.