Hi hardlec,

I'm a newbie here too but have been reading extensively about PM.

My interest is in making some “Yard Art" in the form of a toad stool I saw many years ago while trail climbing in New England (North East USA).  Yard Art needs to be water and critter resistant too ( never heard  PVA can mold as zyggy mentioned but I have never stored it, only used what I mixed) and I live in the South so I choose PVA. 

Looks like methyl cellulose adhesive (Elmer's Art Paste)  would be an option too but it appears to be difficult to find locally.   It would be less expensive because I can get a gallon of PVA for a bit under $10 ( USAD) and Elmer's Art Paste is a bit less than 3$ (USAD) for 2 oz of powder that makes a gallon even though the PVA is diluted 2:1 typically.

In an attempt to make a more weather resistant mixture I use PVA diluted 2:1 as “usual" but I read using Acrylic paint in the mix helps with the weather resistance.

My experience thus far:
My 1st attempt at mixing PVA, water and Acrylic paint.

5 Parts PVA  ( Elmer's glue)
3 Parts water
2 Parts Acrylic Paint

So not exactly 2:1  which would have been
4 Parts PVA  ( Elmer's glue)
1 Part water
1 Part Acrylic Paint

This (not exactly 2:1  ratio)  mixed well and was used to paint the inside of the Toad stool top ( no stem yet) made of cardboard and masking tape.   A day later I mixed up more and used it to make my 1st layer of Papier Mache. It was an experiment on an egg shape made of newspaper and masking tape. It dried overnight and seemed to work well. 

I then tried the “real and proper"  2:1 ratio on another newsprint and masking tape object the shape of a toad stool but a more “organic"  ( less precise) shape than the cardboard and masking tape toad stool I'm saving until I have more experience.

The white Acrylic paint ( I used white but should have used a different color because PVA is white too) is very thick ( maybe like yogurt)  and this 2:1 mix coated and stuck to everything!  I did about 2-3 layers of hand torn newspaper strips. It worked OK but it has taken twice as long to dry at least.

It seems this ratio is best for me:
5 Parts PVA  ( Elmer's glue)
3 Parts water
2 Parts Acrylic Paint

That is, so far, my limited experience.

Zyggy, however, said it best, Sue (Catperson) has amazing knowledge of these things and her knowledge seems to be exceeded only by her kindness and willingness to share it.

I wonder if she has any wisdom with respect to “papercrete" ?

Bob C.

Hardlec, where do you live that you have such a humidity problem, southern U.S.?

I've never had a problem with white PVA glue molding, but even though we have humidity here, we don't have much heat AND humidity like some areas, which could be the difference.

I've never known dry PVA glue to mold, but again, the places I've lived were either hot/dry or cool/moist.  The hot/moist is the killer.  With your conditions, I wouldn't use any food-based adhesive (wheat flour, potato flour, or rice flour), and would limit use to PVA or methyl cellulose (MC or CMC) (it's organic, but so highly processed that it 'shouldn't' mold).

I know David mixes MC with PVA, but I don't.  To find where you stand with the mild issue, I would try both (if you can find MC) separately and expose it to the moisture and see what happens.  It could be that PVA may be your only choice.

The difference between the two is that PVA is a plastic-based adhesive and the MC is highly-refined wood fiber adhesive. 

Jackie has done some research on waterproofing outdoor pieces, so you might want to read her article:  http://www.papiermache.co.uk/articles/w … ier-mache/

Just be sure you cover every single crack and pinhole, or moisture will creep in and destroy your work.

Please let us know if you run into any problems, so the rest of us can learn from your mistakes!  ;-)

Sue

I pour plaster of Paris into molds to make a variety of things.  I have on occasion used it to soak gauze, but it is hard to find pure cotton gauze any more.


I live is west central Florida, USA.  For the last month the temperature and humidity have both averaged over 80.  (80% humidity, temperature 80 degrees fahrenheit.) The mold is ready to become its own political party.

My project is to make an airship model over an armature of 3-liter soda bottles.  I want to make the covering very tough, as I plan to take it to events and use it as a game piece with model airplanes.  {I have a lot of projects in mind for paper mache, as the price of Styrofoam is prohibitive and the availability is diminishing. Also:  I have never liked working with foam.}

Acrylic paint is an adhesive.  I have had many projects nearly ruined by paint "gluing" pieces together.  I have had 3-4 layers of newspaper "soaked" with paint and become hard.
I can go to my local DIY store and get "OOPS" paint rather cheap.  It will have anti-mold agents built in.  I have access to lots of paper, newspaper, roll ends from paper towels, and such.  But I'd rather learn from other peoples mistakes.

Right now 50-50 white glue and water looks like a good option.  I will airbrush on the final coats of paint.  However 50-50 water and paint would work fine too.

Just keep in mind that acrylic/PVA materials tend to be more 'water-resistant' than actually waterPROOF.  PVA glue is not waterproof by any means.  Coat something with it, let it dry thoroughly, then drop it into a container of water.  Turning white is the sign of moisture absorption.

Here in the U.S. PNW, outdoor acrylic or latex paint will still mold.

Sue

I think I will try the OOPS bin at my local DIY stores a few times and see what they have.

There are some paints specifically designed for mold resistance, such as KILZ(r) and I can add some chemicals to the mix if I need to.

I will post progress notes when I have some progress to note.