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question about paper mache pulp

#1 2010-07-27 00:04:16

rosielee
Member
Registered: 2010-07-24
Posts: 24

question about paper mache pulp

papier do and soup im needing your help again.

firstly can i ask- is it me- or do other people also have trouble finding the patience to wait for mache to dry before you start fiddling and trying to get it out of molds and things. be cause everytime without fail i cant seem to wait and fiddle around and then my pulp cracks.

now it may seem a obvious question- and a big stupid one- but what does pulp supposed to look like when its drying?  do you have to wait for it to be totally dry before you take it out or away from its mold? because i tried to have a peek and see if it would come off of its bowl today after 24 hrs drying (this is THICK pulp layer which was full of moisture as i was told squeezing too hard produces lumps) and when i did it was like semi dried but it bloody well cracked- so i had to put it back in and repair- squidge more pulp over the top.

is this normal or is my suspicions about it not being strong enough right? things is- it seems to act like this with or without sawdust- but i etting the sawdust from litter tray pellets- dont laugh- my cat uses them- it would have saved me money if they worked- but dont think they do- im going to have to chat to someone who saws wood and ask if they can give me fresh sawdust- or will sawdust beddng for hamsters do?

do you think i need to add sawdust? ad my whiting- was chalk- blackboard chalk ground by moi- but not ground well enough. you may laugh but how was i supposed t know where to get whiting from. this art business is expensive you know and i have a teenager to look after- bills to pay- seems like when it gets to my art its the last on my priority list- which is absurd really because its the first on my list on whats most important to me (apart from my son etc) so not getting the right exact right materials hasnt helped- but is paper pulp easily breakable until it totally sets and drys? thats my question and am I the only one who cant seem to wait and finds it agony.

im only startin off- so im learning how to make the right pulp- but my theory- my plan- is to have a conveyor belt- so when one is drying- im opening the previous one- and im always working- instead of a week not working when it dries- but it doesnt work like that- becase there is no way im having a conveyor belt of duff bowls-that would be a real waste-once i know i can do one- ill start a system whereby im always busy doing something whilst waiting for mache to dry.

does anyone else find the drying time an eternity and has  anyone else peeked too soon and then had to repair or are you all really well restrained people?

thankyou

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#2 2010-07-27 00:28:13

paper soup
Member
From: Small Town Texas USA
Registered: 2008-08-10
Posts: 107

Re: question about paper mache pulp

Yeah it has to be dry to remove from the form. It will crack every time if it's wet. I have never used sawdust for anything like this, so I don't think that has anything to do with it.
Just think of a regular sheet of paper  You can pick up a dry sheet of paper and fold it or crumple it easliy, but a wet sheet of paper will fall apart in your hands if you try to manipulate it at all. Pulp is pretty much just a super thick piece of paper so the same principle applies.

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#3 2010-07-27 14:01:54

rosielee
Member
Registered: 2010-07-24
Posts: 24

Re: question about paper mache pulp

oh that sounds encouraging- so thats normal for it to crack when wet then, im sure i see some cracks forming on their own- but i didnt have any whiting- i think if i go to gardencentre and buy soe whiting this will really help (hoefully) just wish it tok longer to dry- waiting to see what its lke- its hard.

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#4 2010-07-27 15:15:06

paper soup
Member
From: Small Town Texas USA
Registered: 2008-08-10
Posts: 107

Re: question about paper mache pulp

I think the cracking you see during drying is more due too the amount of water in your pulp. You said that it is really wet and you don't aqueeze it for fear of lumps. The more something has to dry, the more likely you are to develop cracks. It has to do with the drying rates of different portions. Since it's almost impossible to make sure this handful of pulp has the same water content as that handful of pulp, the two are going to be more likely to develop cracks. Also thicker layers are more likely to crack as the outside of the layer will dry more quickly than the inside layer. Drying shrinks the pulp and and this is what is causing cracks.
Have you read the tutorials about making pulp on this site?  They are very very good, and you will see that they advise to get your mixture as dry as possible. Not only does this help prevent craks, but also speeds up drying.
The chalk is a filler, and I think the ground up chalk you are using should work just as well as the purchased powdered chalk if used in the proper portions.
Keep experimenting. Everyone has a slightly different method, and use them for different reasons. Start with one of the tried and true methods  and tweak it until it suits your style. That's what makes the medium so much fun, there is no wrong way to paper mache!
Joey

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#5 2010-07-27 15:25:09

paper soup
Member
From: Small Town Texas USA
Registered: 2008-08-10
Posts: 107

Re: question about paper mache pulp

I reread your post about sawdust. Be sure not to confuse sawdust with wood chips. Hamster bedding and the cat litter are wood chips and much larger than sawdust. The sawdust I think most people use is more like a coarse wood powder than large chips. Try your local hardware store where they cut wood for people. Just make sure you don't get sawdust from treated wood. It has some nasty chemicals in it that you really don't want to be playing with and inhaling.

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#6 2010-07-28 00:22:08

CatPerson
Moderator
From: Washington State, U.S.A.
Registered: 2006-01-09
Posts: 1314

Re: question about paper mache pulp

Patience, patience when waiting for the stuff to dry.  I WISH I HAD MORE PATIENCE!!!  If you have a small fan, it should help it to dry faster.

Sawdust has no strength, it's just a filler.  You know how strong wet sawdust... isn't.

Paper pulp is very weak until it's dry, as it's the adhesive that is holding it together, and the adhesive only holds it when it's dry.  All PM seems to shrink when it dries, but even as it's shrinking, pulp is still very fragile, and will sometimes warp as it dries.  Heat increases warping in any PM.

Paper strips have more tensile strength, and you can sometimes handle it carefully when still damp.  If you use it to line a mold (like a bowl), as it dries, you will see it pulling loose from the mold.

Just keep trying and you'll see how it all works, or doesn't.  Practice makes perfect, or nearly-perfect, anyway.

Sue

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#7 2010-08-02 10:11:01

Pelletor
Member
From: East Coast USA (mid Atlantic)
Registered: 2009-08-05
Posts: 32
Website

Re: question about paper mache pulp

I’m a relative newbie at PM  having only been at it for under two years but would join Sue’s (Cat Person) concern about sawdust not having any strength .   I have made successful variations of pulp and PM “clay"  but have never used sawdust in any of them.  I started off with “tried and true"  recipes to gain experience and confidence and only then did I expand to “fancier"  recipes.  Some of them worked and some didn’t.

About drying:
Air drying in the warm sun and turning frequently worked well for me.
I have used a regular convection oven set at 200º F  for up to 4 hours ( I have a very kind and understanding wife)
I have even used our microwave oven for small pieces and that really worked quickly but just be certain you have no metal inside like a wire armature.  Wire will couple quickly to the microwaves and make a smoking mess or worse open flames.  Did I mention my kind understanding wife?
My most common method is setting the piece in front of a fan.

The adventure continues.......

Bob C.

Last edited by Pelletor (2010-08-02 10:16:58)

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#8 2011-01-18 20:52:03

mavigogun
Member
From: Istanbul
Registered: 2009-04-22
Posts: 106

Re: question about paper mache pulp

I have seen wet/fluffy pulp vacuum bagged over a plaster mold; vacuuming both extracts moisture and applies pressure, compressing and forcing pulp into details.

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#9 2011-01-18 21:38:30

CatPerson
Moderator
From: Washington State, U.S.A.
Registered: 2006-01-09
Posts: 1314

Re: question about paper mache pulp

But you need special equipment for that, don't you? 

I can see myself using the household vacuum... and electrocuting myself.

Sue

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#10 2011-01-19 10:37:09

antoniag
Member
From: Cambs, UK
Registered: 2006-06-10
Posts: 21

Re: question about paper mache pulp

A few suggestions to add to the above good advice:
Work in thin layers - they dry quicker and more consistently than a thick layer.  If you don't smooth them down too much there's plenty of texture for the next layer to grip onto (if you're really worried, paint on some diluted pva/white glue before putting the next layer on).  When I was making bowls I alternated strip layers with pulp, for the reasons given above by CatPerson. 

Make it easier to remove from the moulds - if they're bowls presumably you don't have too much detail to negotiate.  If you start with a layer of wet newspaper (no glue, torn into small enough pieces to fit the mould neatly - it'll stick together enough with the water for this purpose) and then pulp on top of that, you should find it comes off the mould more easily when it's dried.  Vaseline is sometimes recommended as a release agent, to be honest a basic cooking oil (I wouldn't waste the extra virgin olive) will also do a good job.  Or cling film - depends what you're using as a mould.

One of the beauties of papier mâché is you don't need to go anywhere near an art shop or specialist supplies if you don't want to.  Experiment with your 'recipe' - you may not need to use whiting; I mostly use wallpaper paste (for the glue) and standard filler powder (Polyfilla, Tetrion for preference but I'm afraid I don't know the US equivalents) which has a fair amount of 'stick' built into it, with PVA for extra strength and a bit of flexibility.

I've used sawdust but more as a bulking agent in large-scale sculptures than for extra strength.

Hope that helps - keep experimenting, you'll find the method that suits you eventually!

Antonia

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#11 2011-01-19 12:24:16

dopapier
Moderator
From: UK
Registered: 2004-12-04
Posts: 754

Re: question about paper mache pulp

A lot of sensible advice in the messages so far.  I would advise definitely not to use sawdust.  It does not combine well.  As Antonia says, it is good for bulking up but nothing more.  Also use as little water as possible.  The resulting pulp should feel and work like clay.  A calcium carbonate filler is important.  Some people (including me) put in a very small amount of raw linseed oil to help smoothness.
I find the best idea for separating is just damp paper (as Antonia describes).  It means that when you take it out of the bowl you may have to pull some off and apply a layer with a strong paste, sanding it to finish off.
If your pulp is good, you can put a lump between two sheets of plastic and roll it out to very thin.  You can then use this to create your layer.  Doing this seems to condition the pulp, making it easier to work.
Finally . . . yes, patience.  Don't make any layer thick.  Build it up slowly and dry thoroughly.  This way you should finish up with something very strong.  It helps to have several on the go at the same time.
DavidO


I'm a PM addict

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#12 2011-01-19 17:04:03

mavigogun
Member
From: Istanbul
Registered: 2009-04-22
Posts: 106

Re: question about paper mache pulp

CatPerson wrote:

But you need special equipment for that, don't you?

Vacuum cleaner, ridged mold (plaster), and a big plastic bag.

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