Good morning Kossacks and welcome to the thirty-first addition of our weekly home repair blog. Our beloved Claude will be out this afternoon bluifying New Mexico and maybe he'll drop in now and again.
It is also yet another gray day in Stockholm, the 625th or so this fall/winter/spring-ish season and we still have not had any significant snowfall in a long time. Though, my weather widget predict some snow today and this coming week, it's predictability is often off by a bit, still perhaps better than our local weathermen and women- still utilizing those silly cartoonish maps. Correction, I see a few snowflakes outside now.
At any rate, welcome to the virtual table where we gather and chat about home repair Q and A, meta, or whatever is on your mind. By the dictates of tradition, the fair trade coffee is waiting, with fair trade sugar too, some ultra lefty organic Swedish milk too, (mea gulpa- I forgot to by either soy or wheat milk, well not really, I'm back on the cow, for a while at least.)
And, btw, if anyone has any spare time while working or doing remedial tasks that would require an iPod, or just with some background noise, shamless diary pimping yesterday I found Noam Chomsky's Massey lecture Necessary Illusions is online to be listened to publicly as an mp3, and tried to call attention to it. As normal,my diary was gone in 60 seconds. So, if any of you are interested, I highly recommend it, because it is like nothing I have ever heard, and is well worth it. Almost permanant Borki mojo. Please check it out if you have time.
Now back to our weekly scheduled program...
This weeks topic: Urea Formaldehyde
Following comments on plywood and OSB (Oriented Strand Board) from a recent dKos diary based on an article called The Next Slum? featured in the Atlantic, I began to wonder a bit on the nature of using this material in construction- benefits, drawbacks and such, especially with regard to our environmentally conscious attitude these days.
UF, as it is used in the building trades, is primarily a clear thermosetting resin/adhesive known for its strong elastic capability and is used in the binding of various types of engineered building components such as plywood, OSB, MDF (medium density fiberboard,) particle board and a few others.
It was once used frequently in foam insulation, developed in Europe back in the 50's, but has since been discontinued in numerous countries (like Canada) due to formaldehyde emissions during the curing process. It seems as if it is still used in the states, though infrequently, within variances of state or local code. It was however banned in the US from 82, but overturned in 83 and it seems to have been banned in NY in 1980, though I think I used it in Texas in the 90's.
UF was originally used in plastics dating back to the 20's and can be found in a range of household products such as coated papers, drapes and fabric, toothpase (!) and of course, it is most notably, an embalming fluid. Formaldehyde gas is also found in a range of natural processes such as burning wood, tobacco, natural gas and kerosene.
Formaldehyde gas has also been shown to be a carcinogen in lab animals and is a 'suspected' carcinogen for humans, though I'm not sure if any conclusive studies have been undertaken, and there probably should be as approximately 1.3 million to 1.5 million workers in the U.S. are exposed to formaldehyde either full time or part time, and though the article does not state this, I would imagine that this is not from gas alone, but from air particulate through the construction process. Likewise, while I was in architecture school, MDF was banned around 2000 in the wood shop.
As it pertains to most modern home construction, off-gassing in new homes of formaldehyde is a function of the age and amount of the substance present in those building materials, and exposure to heat and humidity, and ventilation. During the first few weeks air levels of formaldehyde gas can be above 0.3 ppm (parts per million), tapering off over time to levels below 0.1ppm, though it is often difficult to determine due to the factors cited above. UF is also noticable in levels above .075ppm, (sweet smell in new cabinetry,) and some people who are especially sensitive to UF experience experience respiratory and other problems at 0.1 ppm.
In order to limit off-gassing, newer plywoods use Phenyl Formaldehyde, a darker colored resin (which can alter the color of lighter woods) and form a more stable water resistant bond. As would be expected, they are slightly more expensive, but reduce off-gassing levels significantly, somewhere around 0.1ppm. And although my trusty construction book does not get into the specifics of the glues per se, structural panels have 3 exposure ratings: Exterior, Exposure 1 and Exposure 2. It mentions that Exposure and E1 panels have a fully water proof glue, whereas E2 is expected to be relatively protected from water- I'd therefore assume that those were PF. (Perhaps this was the point of contention that was not clarified in the above mentioned diary's comments- one user mentioned that the ply he used was resilient others noted how OSB swells with the slightest of water and falls apart.)
At any rate, environmental alternatives to UF and PF are being developed in the form of soy and castor-oil (pdf) based glues, though, I have yet to get my hands on good solid information on them. Some simply say that they aren't UF without saying what they are (possibly PF,) and one in particular claims to be LEED certified.
So much information. I hope that covers it.
Oh, yes, one last thing: in recent news, with architecture and construction being as political as it is, there was recently a really impressive article on the super-incompetence, if not criminal negligence, with regard to the Katrina trailers. It's a good read, especially with the info above.