Why won't my plaster dry?

I'm a dental tech.& use plaster every day a keypiont to keep in mind is if ANYTHING that you used to mix the paster eg. the bowl , the spatula , your hands, or even what you applied the plaster to has come into contact with soap without completely rinceing it off. It will retard the paster and not let it set and even if it did depening on the level of exposer it will not let it be soild . meaning it will crumble in your hands.

what ever You do DON'T paint it until it is bone dry . Be patient .

You mentioned paper towel trick - if that means there is paper under the plaster or in it that's a very bad idea as it will hold water longer .,and keep in mind it takes plaster up to 4 weeks to loose all the water once it sets. If it is setting on a base of some kind that will also slow the drying process. Best to cast your dio base on a sheet of plastic ,than separate the set plaster and place in a very dry place , even in an oven on min . temp. setting .

And its useful for such big areas to add plaster with many coats and leaving each coat to dry.
A hair dryer will speed up everything.

the correct way to mix plaster is to add the plaster to the water.

sift it into the water slowly until it reaches the top of the water and just slightly above so it starts looking like a semi dry river bed.

You will ge a perfect mix everytime and it will set fast.

This is a room in my basement. I moved the dehumidifier in there today to try that. After going all day it had picked up NO water. it is cold to the touch. i did the plastered paper towels trick, then when it seemed dry ( not completely) I plowed a bunch of plaster over it. The dio is slightly bigger than 3' by 7'. Roughly 28-29 square feet. I can't take it outside. I thought maybe i just added too much water or that the escaping moisture has no way to get out. bummer, I wanted to repaint it this weekend.

It all depends on how thick you could've mixed it.... do you mean this past Thurs? Usually when I do up my mixes I usually add tile grout colorant to the mix, and I know I've had to let the stuff cure fully for a week before I could star cutting it up. I can tell it's still damp, it feels cold to the touch, and if I try to work it, it clumps up, another sign it's still got moisture in it. Humidity in the air also contributes to the slow drying time. Give it another few days and give it a check. If it's still damp, you could stick it outside on a sunny day to let the sun get at it.

How’s the humidity where you’re located? If it high it could slow the process.