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#26 2013-12-10 04:17:29

HLG
Member
Registered: 2013-10-21
Posts: 8

Re: Wrinkles/air bubbles developed in papier mache after applying gesso...

Hi Sue,

Ah right, I see - I do the exact same thing quite a lot myself. Particularly when I'm writing out something important and don't want any mistakes. Typical! xD

Yes, I think I'll err on the side of caution and stick to acrylic for this project, though it's good to know that almost any kind of paint is ok for PM. Would a plastic based glue like PVA be affected by solvents, and is that another reason why methyl cellulose would be good for future PM projects?

That's also good to know - I hate the smell of turpentine and/or white spirit, so avoiding them sure sounds good to me. I'll definitely check out the cleanup instructions before I buy anything.

Thanks so much for all your help, Sue - I really appreciate it.

Merry Christmas everyone, and thanks again!
HLG

Last edited by HLG (2013-12-10 04:18:08)

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#27 2013-12-10 07:31:31

CatPerson
Moderator
From: Washington State, U.S.A.
Registered: 2006-01-09
Posts: 1308

Re: Wrinkles/air bubbles developed in papier mache after applying gesso...

"Would a plastic based glue like PVA be affected by solvents..."

You got me on that one!  I assumed so, but I had to look it up.  And the answer is..... Yes, No, and Partially.  Here's a list:

"Solubility of Polyvinyl Acetate in Various Solvents"
http://www.crcnetbase.com/doi/abs/10.12 … 038804.ax4

"... and is that another reason why methyl cellulose would be good for future PM projects?"

Is a guess okay?  Methyl cellulose is hydrophilic (attracted to, and can be dissolved by water).  Everything that I can find that it is used for is water-based:  cooking, pharmaceutical products dissolvable in water, cement, mortars, plaster, grout, paper production and cell culture.

I'm just guessing that it is SO attracted to water that it might not be attracted to chemical solvents or dissolved by them to the point of actually  repelling them.  There's probably a word for that, but I don't know what it is.

Sue

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#28 2013-12-16 12:13:31

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

Re: Wrinkles/air bubbles developed in papier mache after applying gesso...

Toxicity is entirely a matter of dosage- from hyperoxia (breathing too much oxygen) to drowning (breathing too much water).   Compare the MSDS for Krylon matt finish with that of the first bio-epoxy I proffered and you will find that- though they have the same toxicity schedule (2), the epoxy, lacking some of the offending ingredients of Krylon is also not an aerosol -poses less of a hazard; compared to polyurethane- also schedule 2  -the bio-epoxy is far less hazardous.    Without a doubt, the likes of methyl-cellulose- as long as it is not dispersed as a spray -is a whole factor "safer"- by which I mean "care-free as long as you don't put it in you".

After a perusing of contemporary patents, this statement seems simply counter-factual- "It's difficult (if not impossible) to produce a proprietary formula with natural materials."   Oft patents are no more than an innovation in application (rather than composition), while proprietary formulas are... well, just guarded secrets.   Those abound.

Methyl-cellulose does succumb to some organic solvents- yet is resistant to other solvents.   Which solvents attack your binder would be great to know when tackling the choice of mold release agents- or selecting paint.

Last edited by mavigogun (2013-12-16 12:18:33)

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#29 2013-12-16 15:01:55

dopapier
Moderator
From: UK
Registered: 2004-12-04
Posts: 749

Re: Wrinkles/air bubbles developed in papier mache after applying gesso...

Without a doubt, the likes of methyl-cellulose- as long as it is not dispersed as a spray -is a whole factor "safer"- by which I mean "care-free as long as you don't put it in you".
. . . strange, since it is used in beauty products, ice creams etc.  It is generally regarded as entirely safe and non-toxic though, as 'mavigogun' suggests, anything can be poisonous in the wrong setting.


I'm a PM addict

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