After watching my paper mache zombie disintegrate after a month outside in the rain, I knew It was time to develop a waterproof, outdoor paper mache method. The keys to a waterproof outdoor paper mache sculpture are Waterproof glue, Thin-set mortar-mache and exterior house paint.
Instead of paper mache paste, glue, or flour for the outer layer of paper mache I use Flexbond Thin -Set Mortar and a layer of exterior house paint. This method provides a water proof seal that allows you to use traditional paper mache methods underneath to build your sculpture.
Step 1: Materials
Sturdy Cardboard for the frame
Masking tape and packing tape
Blue Shop Towels
Waterproof wood glue
Flexbond Thin-set Mortar
Exterior Semi-Gloss Acrylic-Latex house paint - Black
Acrylic paint - White, black
Hockey Puck (optional)
Step 2: Reference Photos
One of the most important things to have before you start any sculpting project are good reference photos from as many angles as possible. You'll need two master photos printed to actual size to make a cardboard frame:
1 shot front the front
1 profile shot from the side
Step 3: Cardboard Frame
Trace the two Master Photos and cut them out in cardboard.
Cut a slot down the middle from the top of one piece and the bottom of the other. Slide the pieces into place so they are flush at the bottom.
Step 4: Bulk It Out
Scrunch up newspaper and tape it down firmly with packing tape.
Crumpled up newspaper always wants to “re-expand” and you don’t want to try to paper mache over any squishy areas. Keep adding paper until you get the general shape. You won’t be able to get much detail at this stage, but that’s OK. Just get the shape as close as possible.
Step 5: Tricky Shapes
It’s tough to sculpt smooth or detailed surfaces with newspaper.
I added stiff cardboard to get a flat brow and the long skinny ears. I also added cardboard to the bottom to get a flat base. I used a thin piece of craft foam for the curved forehead. Tin foil is great for detailed areas like the nose.
Step 6: Masking Tape
As the head begins to take shape, switch over from packing tape to masking tape for the outer layer. It’s easier to use for detailed areas and the paper mache sticks to masking tape better than packing tape.
Step 7: Paper Mache
Use a mixture of waterproof wood glue and water for the paste.
I use Titebond III Ultimate wood Glue. It’s roughly a one-to-one mixture, but you will have to add a little more water as it begins to dry to keep it from getting too thick.
I used blue shop towels, but you could also use 2 or 3 layers of newspaper. Shop towels are thicker and stronger than newspaper. You can also stretch the strips around curves. They may not be free like newspaper, but they’re worth it!
Step 8: Add Weight to the Bottom
Cut a hole in the center of the bottom, insert a large flat rock, then glue it in place and tape it back together again. This added weight in the center will help prevent it from tipping over in the wind.
I’m Canadian, so I used a hockey puck. We’ve got lots of pucks lying around.
Step 9: Glue-Paint
Mix a batch of waterproof glue and latex paint. I used black, but the color doesn’t matter. Paint the entire head (including the bottom) to form a water proof seal around the paper mache.
Step 10: Thin Set Mortar-Mache
Add layer of paper mache using newspaper and Flexbond thin-set mortar. I use roughly 2 parts mortar to 1 part water. Just add a little water at a time. Keep mixing as you add. Add a little more water as it dries.
Instead of dipping newspaper strips in the mortar mix and applying them, I paint a small area with the mix, dip the newspaper strip in water to get it moist, then lay the wet strip on the pre-painted area. Then I paint more mix on top of the strip you just laid down. I find this method less messy as just water drips off the paper instead of cement. I can also lay down 3 or four strips at a time.
Once it dries, paint another layer of just the mortar mix to smooth it out. No paper on this layer.
Step 11: Paint
Add a layer of black exterior house paint. Let dry.
Then paint a layer of light gray using acrylic paint to make it look like concrete. I applied the gray layer with sponge in kind of a dry-brush method that kept the deep crevasses black to give it some texture. It’s kind of blotchy, but the real Easter Island heads are blotchy as well.
You could also incorporate some brown into your color as well to make it more realistic. I wanted a pure concrete look.
Step 12: Black-wash
Mix a little back acrylic paint with water to get a very diluted black paint mixture (Approx. 10 – to 1 ratio).
It will likely run down the side when you paint the head, but that’s o.k. As soon as you’ve painted a section, wipe it off with paper towel. The black will stay in the deep crevasses to provide some contrast and the light gray painted will darken to a medium gray, more like real concrete.
Step 13: Polyurethane Spray
Spray with polyurethane to seal the acrylic paint. One coat is not enough to make the head water-proof, but it will help a little. You would need multiple coats of polyurethane to be waterproof and it would look too shiny.
Waterproof glue, Thin-set mortar-mache and exterior house paint are the keys to a waterproof outdoor sculpture.
Check out this video on Waterproof Paper mache from DIYeasycrafts.