I have two new experimental recipes for weatherproof paper mache clay, inspired by the giant outdoor pots made by Warren Eggleton back in 2013. I changed his recipe a little, to make sure it would come out exactly the same every time, but it's essentially the usual paper mache clay recipe with Portland cement added to it.

The videos I made when experimenting with the new paper cement clay:
A leaf casting:    • Leaf Casting Made With Weatherproof P...  
Starting a toad sculpture:    • Garden Toad Made with Weatherproof Pa...  
The finished toad, painted and sealed:    • Painting The Paper Cement Clay Toad  

Updates on how well the toad is doing:
   • Update for Paper Cement Clay - Experi...  
   • Paper Cement Clay Update - Is it Real...  

Be sure to read Warren's post to see how his pots were made and how he sealed them: https://www.ultimatepapermache.com/pots

For text versions of both recipe, visit this page: https://www.ultimatepapermache.com/we...

I made two recipes, one that contains the drywall joint compound, and one that doesn't. I tested them both by allowing small sculptures to cure for about a week, and then put them in a bowl of water for a day or two. They didn't soften at all after all that time in the water, but they did get wet. These are not waterproof paper mache clay - but it doesn't look like water will damage the finished sculptures. We still have to seal them, though, because they will get damaged if they get wet and then go through several cycles of freezing and thawing.

I also tested the recipes to see how long we could continue sculpting with the mixtures before they got hard in the bowl, and I had more than three hours of work time in my house at 76° F (24.4 C with both recipes. Warren tells us that we'll have less time to play with it in hotter weather.

I bought my 46 lb bag of Portland cement at my local Lowes. Most DIY stores should carry it. I got the normal grey variety. There is white cement, too, but there wasn't any available locally.

If you try either of the recipes, please come back and let us know how they turned out. If you'd like to show them off or tell us more about them, you can post images of your projects here: https://www.ultimatepapermache.com/da...

You can find patterns for the masks and sculptures behind me in the video here: https://www.ultimatepapermache.com/pa...

The sculpting books I've written, available on amazon.com:
Fast Faces - Unleash Your Creativity: https://amzn.to/2DSNXfG
Make Animal Sculptures: http://amzn.to/1nMUO3a
How to Make Masks: http://amzn.to/2obUDmq
Make Tiny Paper Mache Dogs: http://amzn.to/1KXd9zg

Chapters:
0:00 Intro
0:23 Warren's Giant Pots - the inspiration for this experiment
1:20 Detail possible with new weatherproof paper mache clay
2:41 Problem when I tried Warren's recipe
3:04 My successful test of Warren's recipe
4:30 Why I simplified the recipe
4:47 Why I created two different recipes for weatherproof paper mache clay
5:40 Test pieces for both recipes, after letting them soak in water
6:16 Recipe 1: Weatherproof paper mache clay with drywall joint compound
8:20 Testing the mix to see how long it would stay workable
9:45 Recipe 2: Weatherproof paper mache clay without drywall joint compound
10:34 The different texture between the two recipes
11:34 Why we need more experiments in different climates
12:32 Things to remember when experimenting with the recipes:
12:38 Seal your sculptures before putting them outside
13:37 Why it takes longer for these sculptures to dry
14:17 Why the inside of the sculpture should also be weatherproof
14:57 Why you should never wash your bowl or utensils in the sink
15:52 Summary and my plans for making an outdoor sculpture