DIY Halloween Pumpkin – Made with Plaster Cloth and Grout or Mortar

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This DIY Waterproof Halloween Pumpkin is another one of my experiments.

This time, I’m trying to find a way to make lightweight weatherproof sculptures that can stay outside for long periods of time. In fact, much longer than just the Halloween season. In the next three weeks we’ll see if this combination of products has any promise for permanent yard sculptures.

Spoiler Alert: The experiment appeared to be working well, so I used these same methods to create a Garden Gnome. He’s now been sitting outside through two Minnesota winters, and he still looks great.

Edit 6/24/23 – after four years outside the gnome is starting to see some cracking and delaminating between the grout and plaster cloth. There is now a new recipe that we’re calling Paper Cement Clay, and it seems to be holding up well, but we’ve only had one winter to test it so far. If you’d like to see the experiment, and follow links to some projects using it, click here.

Because the pumpkin was an experiment, I didn’t spend a lot of time designing this pumpkin’s face, but he’s goofy and happy – and I think the neighbor’s kids will like him.

So – why not use paper mache clay? My own experiences with trying to waterproof paper mache have not been successful. And two people who are really into designing outdoor Halloween decor, Rick from the Ghoulish Cop Youtube Channel and Jay from the Unhinged Productions both agree that paper mache clay will soften if it’s rained on, no matter what coating you put over it.

That’s OK if you only keep it outside for a few weeks, for the Halloween season, for instance, and then bring it back inside to dry off again. But most of us don’t want to lug our permanent yard art in and out all the time.

We do have several guest posts on this blog with ideas for weatherproofing paper mache – (just put ‘weatherproof in the search bar to find them) – but we also get reports from people who say those methods don’t work for everyone.

So – it’s time for some experiments.

If you’d like to watch the Hollywood Haunter’s video that inspired this particular experiment, click here.

If you’d like to watch the Unhinged Productions video that talks about keeping paper mache clay sculptures outside, click here.

If you’d like to experiment, too, and make this DIY Halloween Pumpkin, you’ll need:

• Plastic bags
• Twine
• Masking tape
• Plaster cloth
• Flex Bond mortar or Mapai Ultracolor Plus FA grout (the Mapei Flexcolor might work, too)
• Spray clear coat
• Spray paint (orange and black)
• Acrylic Paint (optional)
• LED pumpkin light

Step 1: The plastic bags.

Fill a plastic bag with more bags (or anything that’s soft). Tie off the top. Then use twine to create the dips in the sides of your pumpkin.

Step 2: Cover the bag and twine with masking tape.

Plaster cloth won’t stick to plastic bags, so cover the twine and plastic with masking tape.

Don’t leave the twine end inside of the stem, like I did. That made it hard to get the plastic bags out when the plaster cloth was hard. Tape the twine end and plastic bag ends down tight against the top of the pumpkin. Then make a stem with aluminum foil and attach it with hot glue.

Step 3: Draw a face on your Halloween pumpkin.

Use a marker to draw the face onto the masking tape. You can find some great ideas for a face on YouTube and online. Or just draw a happy face, like I did.

Step 4: Outline the pumpkin’s features with foil.

Use hot glue to attache thin rolls of foil to the outside edges of the features you’ve drawn on your pumpkin.

Cover the foil with masking tape. I didn’t do that. I should have, because plaster cloth doesn’t stick to foil.

Important: Remember to draw a hole for the bottom of the pumpkin. You’ll need it to get the plastic bags out, and to put the LED light inside.

Step 5: Cover the pumpkin with plaster cloth.

I used one roll of 6″ plaster cloth. Cut the roll into smaller sections first, and make sure to keep the pieces away from the bowl of water. They need to stay dry until it’s time to use them.

Use a large bowl of slightly warm water. Dip the plaster cloth into the bowl, allow the extra water to drain out, and then put them over your pumpkin.

Be sure to keep the holes open so you won’t have to do a lot of cutting later.

Important: When you’re finished, throw the water out onto the yard, not in your sink. Plaster will harden under water, and plug up your plumbing pipes.

Step 6: Clean up the edges.

I used a box cutter and my fingers to smooth the edges of the mouth, nose, eyes, and bottom hole on the pumpkin.

Step 7: Mix your hard coat.

Use the proportions of powder and water that are listed on the bag of your grout or mortar. The instructions probably tell you to use a mechanical mixer. I only used a very small amount, and the stick worked OK.

Step 8: Apply the hard coat.

Use a cheap chip brush to cover the plaster cloth with a layer of your hard coat. I used two coats on the outside, and one on the inside.

Step 9: Spay the hard coat with clear varnish

Use any brand of clear coat spray to seal the inside and outside of the pumpkin.

Step 10: Paint the pumpkin.

I used spray paint for my pumpkin. The inside is black, and the outside was sprayed with “Spiced Amber.”

I didn’t spend a lot of time trying to make my pumpkin look realistic, but I did add some light brown acrylic paint to the stem, and some white acrylic paint to the teeth and some reflection lights on the sides of the eyes.

When the acrylic paint is dry, spray again with the clear coat.

Step 11: Add the pumpkin light.

I put my pumpkin light inside a pint-sized wide-mouth canning jar to keep it from getting rained on. Water will go through the pumpkin’s eyes and nose, and we don’t want the light to get wet. You may find a more elegant way to protect your light.

When it’s turned on, your new Halloween pumpkin will look something like this: