Manufactured wood products.

Oddy results for&#3.jpg


Separating reality from "what everyone knows" can be tough, and in our desire to help our colleagues we can fairly easily end up spreading mis-information.
I am pointing the finger right at my own chest right now.
OK, not actually, because it makes it too difficult to type that way.

Anyway, I remember talking to one of my favorite bosses of all time - Bruce Metro - when I first started working for him more than a few moons ago and telling him that I had recently been made aware of how medex and medite were recently failing Oddy tests.

Now I said this like it was a relevation or something.
Why? Because like everyone else I knew I had been told that this stuff was just the thing for building exhibition cases (which on a certain level is fine of course - with a vapor barrier).
Well his response was a moment of silence and a patient look which then proceeded on to a discussion of why that might be the case.
He pointed out the obvious. For some reason up until then I had just bought the story that I was told.
It has happened before and probably will again.
The story with Medex and Medite II or.... whatever is that may be promoted as "formaldehyde free" really just means that the level used is somewhat less toxic in terms of habitation than living in a 1970s doublewide trailer.

In reality though for the same reasons that exterior grade plywoods are considered superior to interior plywoods for use in the museum environment (the use of Phenolic-formaldehyde glues instead of Urea-formaldehyde glues) Medex and Medite II are indeed somewhat superior to particle board or standard MDF (medium density fiberboard). That is saying something I suppose, but not all that much.
What is true about manufactured wood products that they all share is one thing - they are made of wood -- and wood is intrinsically acidic.

Seal anything up in a closed environment with wood and you are creating a bad situation.
Oh for porcelain maybe it is less of a big deal - for metals or paper - it is kind of a big deal.

The image above shows three metal coupons on a glass fiber backing (makes it easier to photograph) from an Oddy test. From left to right we have copper, silver and lead coupons respectively.
For a material to pass an oddy test the image on the right should look approximately the same as the control image on the left.
The good (and some would say bad) thing about Oddy testing is that you get to (have to) use your own eyes and your own judgement to come up with a result.
The blob on the right where the lead reacted to the acids released by the Medite paints a pretty clear picture in my opinion.
The good thing about Oddy testing is just this - you can see results with your own eyes.
The ultimate conclusion to the discussion is use materials both in exhibition case and in storage that pass Oddy tests or utilize a real functional vapor barrier like marvelseal to eliminate the risks to objects posed by the process of off gassing.