Depending on the pulp mix -the extent of adhesive- pulp can be re-wet to facilitate removal or minor repositioning; diluted adhesive may then be washed over the area to cohere what has been worked.

My primary pulp uses PVA and newsprint; it has kept in a plastic tub, unrefrigerated, mold free, for over a year (if anything, it has become slightly more homogeneous).   Any pulp I've used that included raw flour that remained wet soured within a few days.   The problem with thick PVA pulp is that it may dry relatively hard on the outside, trapping minor moisture within, greatly extending the drying/shrinking time.   What a joy to return to a heavily worked bit of sculpting -that you thought was finished- to find it looking emaciated.

"If I'm working on something large or intricate, or I simply work to slowly,  would the pulp not simply dry up and become unusable?"

You may be looking at a benefit as a detriment.  Try turning it around.

IMHO (well, IMO, anyway), a large lump of wet pulp is not something I want to keep wet.  I've always seen it as better to get the basic shape going and then get it started drying.  In fact, I would prefer it get completely dry, so it becomes stronger and more rigid.  Then I can add another layer, smooth it down and let it dry, too.

A big, thick, damp, gooey mass is extremely hard to dry thoroughly.  PVA adhesive, in particular, seems to form a sturdy skin on the surface, limiting how much moisture can evaporate from the mass.  Some people say they don't have a problem, but they must be doing something different. 

I made a great cat over a glass bottle... I think it was my first experiment with paper pulp and PVA glue.  How long could it take to dry in sunny Southern California???  Well, I thought it was dry, and it wasn't.  I guess the surface that was right against the glass didn't dry, due to lack of exposure to air.  I sanded the cat, painted it, sealed it.  It wasn't right away that the colors started changing, maybe a month.  The moisture had apparently worked thought the piece and mold was building up.  All the lighter colors became dark and murky.

So now I go with the 'Dry as You Go' Plan:  Apply, dry, apply more, dry more.  It's part of the PM Learn-As-You-Go learning process, I guess.

Sue

I was using pulp with PVA (white glue).  The outside was dry when I tried to dig my fingernail into it.

When the mold took over, I sawed the bottom of the PM off and then pried and ripped the body off the bottle.  The inside of the PM was black with mold.

IF I had designed it so I could remove the bottle when it was moderately firm, and then let it dry with the inside surface exposed to the air, I probably wouldn't have had the problem.

And IF I had applied thinner layers instead of a thick one, I probably wouldn't have had the problem.

The Benefit:  I DO tend to recognize a mistake when I make it again...

Sue

This mystery is growing mold.

I'm on the east coast of England so it is not as wet as most parts.  Nevertheless I would never expect to create pieces with great splodges of pulp.  Build and dry in layers and all should be safe.

Interesting conversation so far.  It's good to know that the glue drying thing won't be an issue, and that it keeps pretty well, which was my original question in point.  Perhaps I should have been more specific that I plan to do pulp painting (without glue) and pulp "bas relief" (with pva glue) 2D sculpting, nothing large or 3D in nature. These items would not be very thick in the least, so the final drying and mold growth should not be an issue. (I hope!)  If I do make something 3D later on, the pulp would only be a final, thin overcoat (with glue) over an already dried form.  The time issue is simply a personal one, as I'm very OCD and even the smallest sculpting detail needs to be "perfect" and I could end up spending forever working on it, (like hours, seriously) so the pulp staying workable is important. =P