# Packing and Crating > Crate Shipping and Storage >  Climate control storage for Traveling Exhibition Crates

## T. Ashley McGrew

I thought I would put this response just posted on the RCAAM Listserve here on the PACIN site.

The original post was on a common topic and consisted of the author asking about why crates should be kept in a climate controlled environment during the show even when empty. 

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Hi All,

As something of a crating geek I am always surprised when this question comes up.
Back in 1991 a long standing mystery was finally answered - resolved by actual documented, systematic testing.

The documentation came in the form of "Art In Transit" a workshop and the related two publications that was then, and still remains the most comprehensive and authoritative reference on Art and Object Crating to date.

The ongoing mystery I mentioned was just how so many exhibitions that included works on paper could come through our museum with condition reports that in no way reflected the reality that I would find as I opened the crates. 

Many of these objects showed extensive cockling and in some cases spots (foxing?) that were not reflected in very detailed condition reports written at previous exhibition venues. 
These venues were very often quite reputable museums presumably with adequate climate control within their galleries to prevent what appeared to be humidity related conditions that were appearing during the course of the exhibitions tour.

At Art In Transit simple testing with data loggers placed on Paintings frames as well as on the on the exterior and interiors of the crates they traveled in revealed that crates stored in non-climate storage environments then duplicated those conditions for the art work contained within them when shipped to the next venue. So this has been a known aspect of Traveling exhibition protocol for quite a while now.

Unfortunately there seems to be an idea out there that "The air inside the crate with the art when it was closed up was from a well maintained gallery so it should be fine."
Another common misconception held by those who are somewhat familiar with the need to store crates in climate controlled environment is that "If we have the crates brought into climate control 24 hours before packing it should be fine right?"
Of course neither assumption is accurate.

Commonly used crates made with wood and engineered wood products as well as many of the materials used in the interior of crates (different types of boards and foams) are hygroscopic in nature. In other words they absorb and store moisture. 

If you for example place art or objects in a crate that has been stored in a high humidity environment you are essentially creating a situation similar to placing them in a baggy with a sponge.

Even if the conditions outside the crate are ideal during transit what is created inside the crate is essential going to match whatever the conditions were that the crate had become acclimated to.

While it would be nice if a 24 hour period would be enough time to correct the situation, the physics of it don't really work out that way. 
The 24 hour guideline is intended for use only in regards to temperature change which takes place much more rapidly than changes to the moisture content of solid materials.

The impact that this variable will have on the safety of your objects is relative of course. 
It is the result of a complex equation that includes the innate sensitivity of the material you are shipping, the type of crate you are using, what kind of interior seals are used, and obviously the nature of the unconditioned climate that your crates are exposed to.

There is less concern for example here in LA where the weather is relatively temperate year round as compared to other areas in the country and world where changes can be quite dramatic.

That said, even under more moderate conditions the best quality crate - sealed with a very effective vapor barrier like Marvelseal - will succumb to its storage environment over the course of three months of storage.

In short I would conclude that if you are mindful of issues like the storage of your crate(s) then they can do an excellent job of protecting the important objects in your care. 
If you dont, they can actually represent a significant threat to the safety of the very objects that they were designed to protect.

For any of you who were stalwart enough to read this far I should mention that I am pretty sure that at this time, both the Art in Transit publications are out of print.

The Studies in ... bound version was going for just a bit under $300 dollars last I checked, and even then copies are hard to come by.

Art in Transit: Handbook for Packing and Transporting Paintings however is available as a PDF from the Smithsonian Digital Repository by clicking HERE. 

This link along with others can currently be found in the Of Interest tile on the front page of the new PACIN website.

Best wishes of the season!

Ashley 

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Please help fill in on this topic when you are able to get to it. 
Thanks

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