Very humid here in Tampa area. Would it help to seal up the ends of the wasteboard since it is mdf ?
That would not hurt
I think MDF is pretty stable in humidity. Just don’t let a puddle form on it.
Can confirm that my unsealed MDF wasteboard has expanded in the damp Welsh climate. The edges have also gone a bit grey-green. We’ll seal the next one.
You should seal all 6 sides of your waste board to promote even moisture transference.
Even with a finish, moisture will move in and out of the MDF, just more slowly.
The edges are more prone to this activity, so you will likely need to resurface a bit more often If the humidity in your area changes seasonally. It swings radically from winter to summer in northern Minnesota so I need to skim mine once or twice a year by just a little bit.
To do so, I set my z zero at the center of the board, then raise the bit by .01 and reset the z zero and run a file I created to skim the board, this prevents hogging things off If the board is really bad. I can always run the file again after another z zero reset.
just mix a little wood glue and water and brush it on, only takes a minute.