Scroll Down there's lots of good information here. Click on the Picture too.
I am conducting my own tests. I will report these to you as we go. But dont let that stop you from gaining experience too.
Consider: How thin is tent cloth? If I can make it stand up by itself, and make it cheap too, Im a hit.
The glue wasnt cheap, except for this small test. But I needed to know how it works. After all, I need to be able to do something, in spite of my handicap, before I tell you to do it.
If its thin, flexible, and can hold up wet NFRC, is cheaper than chicken wire, and can help the NFRC to cure. Thats a good goal. Then you can make your pink froggy, or geodesic dome if youre conservative, much cheaper, and help accomplish the goals of the Green Island Educational Center. Of course, you could just waterproof the paper, but it wouldn't be as tough or long lasting.
I overlapped each papers edge by about 2 inches, so that any tensile forces would be properly transferred.
It turned out excellent. All of my goals have been met. It is reasonably flexible, and sags under its own weight. Is that bad?
Not if used properly. It means that it would be a good form for holding more rigid NFRC. You can build it flat, and then tie it in place with string in the shape of your shell. Then place more durable NFRC on top.
One question is, is it less expensive than chicken wire? What is the value of your labor and the time involved? Since it can be made on painters plastic drop cloths, it has a reasonably flat texture on one side, even if the other side is a bit wrinkly. If placed as a "Beautiful Form," or armature, that remains inside your shell, the chicken wire texture does not appear through the paint.
It can be made flat, or the plastic drop cloth can be drooped to produce the curve you like. Of course, the drop cloth wont fit a compound curve, but you can fold it with only slight surface marks held with masking tape. And they are big like your froggy.
An average dome or pink froggy is 30 feet in diameter. So its radius is 15 feet, which is 180 inches. My test piece only covers a 24 inch portion of that circle, so in the middle, 12 inches out, it sags just 1.2 inches. So I can recreate that curve in NFRC and see how it works.
Now, assuming you get the fiber, even paper free. At Home Depot it costs about $0.04 to get enough diluted glue to cover one square foot of surface area using wallpaper paste and 4 layers of free paper.
Whereas it costs about $0.21 per square foot with chicken wire.
At first that sounds like a no-brainer. However, the chicken wire can be formed into complex curves of all sorts of shapes, whereas the paper mach may be difficult to form, even when doing pieces. Typically, it takes 3 days, and a whole high school crew to build a paper mach float using chicken wire. How long, and what methods would you use to form your project making flat pieces on plastic? However, geodesic domes are made with flat pieces, but have to be lifted in place.
Its a trade off. You have to look at what you intend to build, and decide for yourself.
2. When dry I made slits to make the curve 24-inches. It didn't like being cut, it was quite hard, and brand-new sizers had difficulty cutting only 4 layers of paper. I inserted string, (which you can barely see because it's white,) to curve it to match a 30-foot shell structure. (A dome, piggy, froggy, or whatever.) Next I'll put a thin layer of stucco to see how it will work.
The string was stretchy, so it held the paper mach, but not my weight upright, but then, neither will tent cloth.
3. The 3rd test was a failure! As you can see, (one week old,) a thin layer of stucco, (or mortar, mixture is the same,) was put over 4 layers of dry paper mach that would act as a form. With slight movement, the stucco broke, and came up. It had no fiber, thus it had no tensile strength, and didnt do the job.
The stucco failed to glue to the paper mach. That can be a good thing if you intend to remove the paper mach. Or it can be a bad thing if you intend to leave it. The stucco broke up in pieces when I pulled up on it. I dont believe it would make a good froggy.
4. Mortar + Paper, failed! As you can see, the mortar failed to glue the paper together, as the diluted glue did. So we will have to try a different approach to achieve both a waterproof and a structurally sound method thats inexpensive.
So far, the paper mach works better, even though not inexpensive enough.
To waterproof and paint it, Home Depot advertises pool paint, if you like to have a blue froggy. Its waterproof, and requires two coats, for $3.21/sq. ft.
Heres what they advertise:
For all in-ground masonry pools. Unique Acrylic Formula designed for underwater use, Resists UV damage and Pool Chemicals for lasting color and durability, Resists mold, mildew and algae, One coat covers 250 sq.ft. per gallon. 2 coats are recommended. For example = a 15 ft. x 30 ft. pool requires 6 gallons to properly paint. Provides a decorative waterproof coating for all masonry pools. Unique waterproof formula is specifically designed for under water use. For use over all previously painted pools. Semi - Gloss finish. Clean tools with soap and water. Self priming on all properly prepared masonry pool surfaces. Actual paint colors may vary from on-screen and printer representations.
This should work well on paper mach for your froggy. Try it and see.
So, if you built a 30-foot hemisphere dome, with the waterproofing paint at $38.97 per gallon, 2 exterior coats, should cost $440.83 to paint just the dome exterior.
5. Next test is underway.
Thanks for your interest.
The information presented here is strictly educational, and neither Dr. Hait, nor the Rocky Mountain Research Center have any responsibility for your project.