Des..i..what?

newtrall

Grumbler in Training
Joined
Mar 11, 2004
Posts
9
Location
Jackson MI
Recently one of my vendors placed a flyer in with my order stating that they now sell Desiccants. You know, the little silca gel packets you find in shoeboxes. Only this type is all clay especially for paper documents.
Anyone use them?
Is it possible to remove too much moisture from pieces?
Would it be a nice up sale for high humidity areas?
Do you just throw will-nilly into the back of every frame job?
just wondering.....
 
Silica gel has a saturation point at which it will no longer absorb moisture. The only way to “reactivate” the stuff is to shove it in an oven for a few minutes and dry it out.

I wouldn’t think it would be too practical in a picture frame.
 
The type of silica gel that works best in a frame is the Artsorb type, that is bonded into a 1/8" or so thick flexible matrix.

It can be ordered to a specific RH in the 40% - 60% range, but in order to keep it's RH, it must be put in a sealed framing package a la Hugh's Marvelseal/glass/hot melt glue or tape package.

http://www.fuji-silysia.co.jp/english/product/humidity_control_silica/art_sorb.html

As far as RH goes, the lower the better. Paper becomes more brittle as the RH decreases (and therefore more difficult to handle in the 30% and lower range)but the low RH protects it from degradation reactions which require water (vapor or molecularly bound) to occur.

Hope this make sense!

Rebecca
 
Bill and Rebecca are spot on with their info.
If an airtight seal can be made (which is almost impossible with a normal frame) then it would have some benefit.
But, be very careful with this product.
The sealed packs are reasonably safe, but raw crystals can produce cariogenic fumes / dust particles when handling and drying.
One of my flower preserving lady customers here, who now has a freeze dry machine (but used to dry with bulk silica gel), advised me a few weeks ago that she discovered drying it out in the microwave or oven (as she used to do) is highly hazardous without correct safety equipment and processes.
 
Desiccants can be damaging in some circumstances. They serve to balance the moisture content of their surrounding air. Depending on how the desiccant is conditioned prior to closing the frame, it could maintain more or less humidity than what is in the ambient air. Of course, it must be properly conditioned before assembly.

The danger in "real world" consumer use is that the owner might accidentally or unknowingly expose the desiccated frame to extreme humidity, and the desiccant could re-condition itself to that extreme moisture level. For example, window cleaning solution could be absorbed into the desiccant, as it wicks into the boards of a frame, building up the RH and filling the desiccant with water over time.

Once accidentally re-conditioned, the desiccant would try to maintian the too-high RH in the frame. When humidity drops, it would release mositure.

A properly fitted & finished frame allows the whole assembly to slowly acclimate to its surroundings, but insulates it from fast or extreme changes. In a way, that minimizes the need for a desiccant. But in another way, it amplifies the re-conditioning danger.

I've used desiccants only a few times, for customers who were aware of their characteristics. In most consumer framing, they are not needed and could cause problems.
 
This link is more useful than the previous one if you are interested in the sheet form of Artsorb.

http://www.consemp.com/catalog/i.html

I believe you can order it in sealed packages conditioned to the appropriate RH. Or, if your environmental conditions are in the right range (40% is good) it will adjust itself to ambient conditions.

And, as Jim says, the frame must be sealed if you use it.

Rebecca
 
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