How is medium Density Fiberboard made?

Medium density fibreboard is made from wood chips, shavings, sawdust, and low-quality logs mashed to a pulp and mixed with an adhesive before being pressed into panels.

It is made by a machine that compacts all the materials in it all into one thing.

It is not going to have enough strength to use for a shelf, it will sag.

The differences between medium density and high density fiberboard (mdf and hdf) do vary slightly between manufactures. These are some general facts. MDF is a product of soft woods that are broken...

Well one of them is kind of dense while the other one is not really dense at all.