Water-proofing papier-mache...how can this be done, please?

Hi, Thanks for stopping by! I would like to do a large (2m2) outdoor papier-mache project. Essentially it's a large plant holder display and so would need to hold about 25lbs in weight and be able for me to water the pot plants it will hold. These are my concerns, and I would seriously appreciate some advice if you can: - How do I waterproof the whole thing? I was hoping to use strong wallpaper paste and then seal it with about 3 coats of oil-based paint like eggshell. The other worry I have is where I cut holes into the papier-mache there will then be an unsealed exposed edge where water could get in a separate the layers: I don't feel that paint would be sufficient for such thin areas/egdes...what would you do? Again, thanks for reading me, please help if you can. Kevin

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LadyZandra25 years ago
Oops! Forgot about your cut edges! Simply add another layer of Mache strips to seal the edges... Since using it outdoors-- add glue to your mache-- a water-based glue that dries "water resistant" helps-- like carpenters glue.
LadyZandra25 years ago
1st- be sure to use a wood/chicken-wire type base to hold the weight-- maybe even a stepping stone/paver in the bottom for windy days!
As for weatherproofing-- all you need is Marine/Yacht varnish. Use good paint- several layers-- then 2-3 coats of varnish. Know to last outdoors for a couple years-- or at least 1 year with a harsh winter & lots of rain! Good Luck! Post your project when done!!!!
Gorfram8 years ago
Caitlinsdad mentioned a cement slurry - There's a method for making pre-mossified faux-stone planter pots out of what's called "hypertufa," which is a mixture of perlite, portland cement and moss (google "hypertufa" for a deluge of info & how-to's). I wonder if you could use this in the planter interior, and gradally introduce more paper and plaster-of-paris while reducing perlite and cement as you work towards those surfaces that require a paper-mache finish. (Note: the dust that comes of off dry perlite does nasty, cancerous things to lungs; but wearing a cloth or paper mask will block it.)
kevinhannan (author)  Gorfram8 years ago
I had heard/seen of the technique before on the tv,but I had no idea what it was called - thanks for that! I'm always frightened of learning something new everyday! lol! It's an interesting idea and one that has intrigued me. I am certain to a few Easter Island Statues and perhaps a Totem Pole (biy, do I like to piss my neighbours off! (te he he!) so I will also do this one. Thanks again, and I hope your day is a good one!
kevinhannan (author)  kevinhannan8 years ago
soz for spelling - my screen and keyboard are tiny
kevinhannan (author) 8 years ago
Thanks guys, I appreciate your comments very much. I'm sorry it's been a while since I replied: my laptop broke and this is my first time online since then... So, thanks again, and sorry again! kind regards Kevin
If you make these with glass-fibre resin, or cheap slow-setting epoxy glue you'll end up with something very tough and waterproof. But it won't be that cheap. If you give it a good coat of varnish you should be OK, but as you've already observed if you break the surface there's potential for water-ingress - cut and varnish the holes heavily. L
kevinhannan (author)  lemonie8 years ago
Yes, cheap is my middle name! I'm going to sit on this one for a while; I enjoy being able to say my projects cost less than a £1 or £5 depending on its scale and application... your comments are sound though and should work; I'll sit a while before splurging the cash that I don't have! cheers lemonie! kind regards Kevin
caitlinsdad8 years ago
You might need to take the following approach. You need structural strength as well as waterproofness so why not make it waterproof throughout as you build it by using a resin of some sort instead of glue. Maybe use a gallon of marine varnish as your glue. You may even want to use cloth strips and a slurry mix of cement or mortar and then make your piece. It would be outdoorsy stone-like looking or then you could use an exterior rated paint. Good luck.
Kiteman8 years ago
Ordinary varnish should do the job, but you'd have to make sure the mache was very dry before sealing it, and use several layers of varnish because it will soak in more easily than into wood.