The balloon is nothing but temporary support.  Are you using a true balloon (which will deflate very soon) or one of those balloon-type balls that can hold air for a considerable length of time?

While I have never taped cardboard to a balloon, I think you're still okay if you have applied any papier mache to the cardboard, which should help to support it.  If you haven't yet, you may just be where you started before you applied the cardboard to the balloon.

May I assume that the cardboard is part of the mask itself, and not just a support?  As long as you don't get the cardboard too wet, it should be strong enough to support itself when the papier mache is applied.

You didn't say what kind of adhesive you are using... flour and water?  White glue diluted with water?  A cellulose-based wallpaper paste?

Flour or cellulose glues are organic, and should allow moisture to work through several layers of papier mache (3 or 4), which shouldn't affect the cardboard unless it was very wet.  White glue is a plastic type of glue, and I have had problems with it not drying thoroughly when several layers have been applied.  It seemed that the surface dried but the stuff underneath remained kind of soft and rubbery.  Some other people here will disagree with that opinion, and think it dries fine.

The number of layers may vary with need.  On top of a fairly solid piece of cardboard that wasn't allowed to get so wet that it got deformed, you would probably need fewer layers than you would if you hadn't used the cardboard.  Let the whole basic thing dry well and then gently test it to see if it's sturdy enough for your purposes.  Newspaper (if that's what you're using) might be a little softer than computer paper or rice paper (washi paper).

Heat can dry the piece faster but it also will usually warp the piece, so it's safest to hurry the drying with a small fan at room temperature.  As the air passes over the papier mache, it will carry a bit of moisture with it. 

I would probably apply two layers and let it dry between.  Sometimes I've done three, but I am rather impatient... You might try two layers all over, then apply a third layer just in one patch and see what happens.  Does it slow down the drying in that area?  Papier mache is always a race between what is best and how much time you want to wait, and what type of paper and which adhesive you've used.

If the balloon is still inflated and the piece is completely dry, I think you could remove the balloon before you paint it. 

I understand that emulsion paint in Britain is the same as acrylic paint in the U.S., and that is plastic-based, so it will act as a type of sealant, but since it is water-based, avoid the temptation to slop on a thick layer two reasons:  first, it can re-wet the papier mache to the point that it gets soft and causes problems, and second, it always looks sloppy and gloppy and requires a lot of sanding to look smooth.  Apply several thin coats, instead, with a minimum amount of paint on the brush for a more professional finish. 

Don't apply a final sealant like varnish or clear polyurethane until it is about the last thing you do.  Applying paint over varnish tends to result in the paint being scratched off very easily.  The clear sealer should be the final, protective coating(s).  (There may be a few exceptions to this, but I can't think what they might be.)

Also, if someone is going to wear this mask for more than a few minutes, you'll want to give the inside several coats of true shellac to protect it against body moisture and perspiration, as it is non-toxic when dry.  If the mask is intended as just an art object, you can use the outside sealer (varnish or polyurethane) on the inside, too.  Always remember with papier mache that BOTH sides should be sealed whenever possible, as moisture from the atmosphere can damage it from the unsealed surface.

Have fun making the mask, and let us know to look in the gallery if you decided to post a photo of the finished work.

Sue

Yes, damp mache with tend to cave-in a tad if the balloon deflates before it's set enough, although it can produce some interesting shapes it's not necessarily practical if your going for a highly defined form in the first instance.

Even cheap balloons will remain inflated for a good while though before you need to worry about them ... unless you pop it to see what happens, curiousity killed the papier mache cat perhaps?!

My current WIP uses a six inch diameter balloon to form a head piece, it's now got about 10 - 12 layers on it.  I tend to just keep checking it's strength by gentle pressing and seeing how much resistence I get though rather than going for specific number of layers ... generally I apply two or three layers and allow 18 - 24 hours to dry, although this may have more to do with my routine than anything else.


ETA:

There are no hard and fast rules for papier mache, try what you think.

Last edited by Alasdair (2009-03-17 16:38:35)

Isn't the US equivalent of emulsion called "household" latex? The type you buy in big cans to paint the walls of your house.

Thanks for all your help!  My mask turned out really well (and strong).  I'll put up a link to a picture of it soon.