Many of the home design shows on network TV love to use MDF for their projects. It is easily painted and is cheap to purchase. If you purchase a bookshelf at a local department store it is often made with a particle board covered with a paper veneer. Can either of this material hold up over time with 100 pounds of books on them? I have seen first hand that particle board will barely hold up to a stack of paperback novels.
There is a great calculator for figuring the deflection of a piece of material under a pre-determined weight. The Sagulator can be found as an online calculator at http://woodbin.com/calcs/sagulator.htm
In both cases we will use a 36 inch wide shelf that is 12 inches deep. The assumed weight for the shelf is 100 pounds. Below are the results:
- ½ inch MDF will deflect .97 inches.
- ¾ inch MDF will deflect .21 inches
- ½ inch particle board as used in department store products will deflect 1.22 inches
There is not much difference between the ½ inch materials used. Stepping up to ¾ inch thick material greatly improves the strength of a shelf.