Waterproofing Paper Mâché Experiment Results

After the ball was cut off the Styrofoam ball and put back together.

Last week I started an experiment to see if a product could help waterproof paper mâché.  Many of us who work in paper mâché want to make items that can be used outside.  Paper mâché objects do not fare well in outdoor conditions since it is made from paper, flour paste, and water.  Painting and sealing with an exterior sealer help, but even that has its limitations. Items left outside overlong can be subject to water getting into the paper mâché and collapsing.  Last week I started an experiment to see if a product could help waterproof paper mâché. Today, I am reporting the results of the experiment.

The ball soaking in a tub of water.  It floated.

I will recap the experiment briefly.  I covered a Styrofoam ball with masking tape and then covered the tape with a layer of Press and Seal, a product available in grocery stores to cover food.  I covered the Press and Seal with three layers of newsprint soaked in a flour and water paste with some thin set mortar admix added at roughly a one to one to the amount of water. (I will describe my paper mâché methods in more detail below.)  After three layers, I used a craft knife to cut the dried paper mâché layer from the ball.  I cut it into four sections to remove the ball because I wanted to use the ball in other projects.  Using hot glue, I glued the sections back into a ball.  After the ball was back together, I covered it with three more layers of paper mâché.  The paper mâché ball had no other paint or sealers to protect the ball.  At that point, I was ready to see just how well a wet ball would hold up if it was placed in a container of water and left to sit for an extended period of time. 

Water infiltration above the waterline.

I put the ball in a container of water, making sure the ball was well soaked with water all over.  The ball floated.  I checked the ball at five minutes, ten minutes, half an hour, one hour, one and a half hours and two hours.  The ball floated the whole time.  After an hour, the section of the ball above the waterline had dried completely.  At an hour and a half, I began to see a few places where water seemed to be infiltrating in a few small places above the waterline.  I was unsure whether the water infiltration was caused by the ball moving around as it floated in the container.  At two hours, there was a definite line where the water was creeping above the water line. 

Completely dry again.  No edges came loose.

At two hours, I pulled the ball out of the water to see how badly the water had damaged the integrity of the ball.  The outer layer felt slimy, but the ball still felt solid.  I decided to end the soaking part of the experiment and see what happened to the ball as it dried.  After a few hours, the ball felt dry. 

By the next morning the ball was completely dry.  It is solid with no collapsed areas from having been wet.  None of the strips of the paper had come loose or pulled up on the edges.  Everything was as well glued down as when it went into the water.

I guess my conclusion is that by adding the thin set mortar admix that it did help to some extent in waterproofing the   paper mâché.  I will now be testing to see how well paint will work over this type of mixture.  If it holds paint well, and with additional sealer on top of the paint, it will add another step to making paper mâché be more outside friendly.  I will be reporting on this as things go along.

I am kind of annoyed with myself in one aspect.  If I had taken the time to make a extra ball with a standard  paper mâché mix, I could have compared the difference between the two mixtures and how it affected the ball.  I would also have liked to tried this experiment with the penetrating sealer I wrote about when making my last pumpkin.  Unfortunately, I did not have any more, or at least not enough for the project.

The method I used to make the  paper mâché ball. 

Please note:  I used eye protection and gloves while making and applying the mixture. When working with paper mâché you need to protect your work surface and flooring with plastic or some type of drop cloth.

I have worked with paper mâché for so long that I don't measure ingredients anymore.  The amounts would change depending on the size of whatever I was working on at the moment.  My basic method of making a basic paper mâché slurry would be to put flour into a container and add water a little at a time and stirring between additions.  I stir until the lumps have disappeared and the mixture is a smooth paste.  For this mixture, I modified the approach a little bit.

I mixed the flour with water only until it formed a stiff, slimy dough.  I wanted the action between the flour and the water to start setting up the gluten reaction.  Then, I added about an equal amount of the thin set mortar admix to the dough.  I kept adding the admix a little at a time and stirring between additions until the mixture formed a smooth, thick slurry.  If you have worked with paper mâché for a while, you will recognize the appropriate texture of the mix.  If you haven't the general rule of thumb is that if it is hard to spread and forms lumps, it is too dry.  Add more water (or admix in this case)  If the paper gets overly soaked and does not stick well it needs more flour. 

For the paper part, I used torn strips of newspaper.  I spread the paper mâché mixture on the strips of paper with a disposable foam brush.  I like this method because it is less messy than dipping the strips in the mixture.  Also, if there are small flour lumps, I can brush them off the strip easily.  That means fewer lumps on your project, which means less sanding.  (If you are inclined to sand that is.)  I add a single layer of paper mâché and let it dry overnight before adding the next layer.  If you do multiple layers, there is more potential for mold to develop.  This takes longer than doing multiple layers, but overall I have found it more successful than adding more layers at one time.

Future Blog Posts:  I have been working on another pumpkin and I will have photos of the new one in about a week.  I may post one other post in between on another subject (to be determined).  I am trying to get back into posting twice a week, but there is not much to write about when stuck at home trying to wait out the Covid-19.  However, a few humorous things have occurred that may be worth writing about just to keep things from being so quiet between posts.

An Experiment and a New Paper Mâché Project

The small ball for the experiment.

Regular readers know that I always have to experiment on techniques with my projects.  On my last  paper mâché project, I tried sealing the piece with grout sealer before I painted it.  I wanted to find a different way to seal the paper mâché against moisture.  I planned to give the piece a couple of coats of sealer after it was painted as well.  Unfortunately, I ran out of the product.  With Covid-19 wrecking havoc everywhere, it might be a while before the piece is sealed. 

Pumpkin halves removed from the form.

While I am waiting for more sealer, I am on to a new experiment with a different product.  We had some thin-set mortar admix left over from one of our home improvement projects.  The milky-looking liquid polymer is supposed to be mixed in a one to one mixture with water and added to thin-set mortar for tiling projects.  It is supposed to help increase the bond and add water/moisture resistance.  I thought that being as I had time on my hands that I might check it out to see if it worked in making paper mâché items.  I wondered about its potential to moisture proof the paper mâché.  So, time for a new experiment.

My first pumpkin is painted but not sealed.

For my experiment, I wanted to know just how long an item made with the mortar admix might be able to resist water.  I wanted to know how long an object made of paper mâché mixed with the admix but not painted would last while soaking in water.  I thought that test would really put the product to the test.  That is the experiment, but before I can try it, I have to make a test object. 

One of my plans for a Halloween decoration was to be some glowing orbs.  The orbs would be paper mâché and spray painted with glow in the dark paint.  I decided that I would make a small ball for the experiment.  (Long time readers might remember my fascination with spherical objects.) 

I used a small Styrofoam ball as a base for the orb.  I covered the orb with masking tape, and then covered the tape with a layer of Press and Seal.  The  paper mâché will not stick to the Press and Seal.  Once I cast three layers of the paper mâché mixed with the admix, I cut the layers off the Styrofoam ball using a craft knife.  I always remove any base I use from my completed projects.  When possible, I try to use items more than once, so I carefully cut the paper mâché away from the base in sections, keeping the base intact.  That way, I have the ball to use again for another project.  For example, I used this same ball to cast the eyes of the pumpkin I made and blogged about in my last post.  Now that I have removed the ball from this project, I will use it again in some other project.

Before I cut the ball off the base, I made some registration marks on the ball so I know how to put it back together.  I have learned from experience that I need to number the marks, so that it can be realigned with its proper counterpart.  I could not remove the ball from the paper mâché layers when it was cut in half without damaging the ball.  The paper mâché was taken off the base in four sections.  Three layers of  paper mâché are not enough layers to be completely rigid.  It is easier to remove the paper mâché while the form still has some flexibility. 

Once the ball was removed, I used hot glue to put the ball back together matching the numbered marks.  I use hot glue, gluing it along the cut edges.  The flexibility of the three layers makes it easy to put pressure on the form to glue it together without too much of a raised edge. 

Once the ball was glued back together, I add three more layers of paper mâché.  This covers the cut edges and is strong enough to keep the ball from coming apart.  At this point, I have added two of the three layers to the ball.  Hopefully, tomorrow I will have time to put on the last layer.  After the last layer has dried for twenty-four hours, I will be ready to try the experiment and see how long the ball will last while sitting in water.

In the mean time, I have also started on another pumpkin.  So far, I have cast the paper mâché for three layers over the pumpkin form I created.  (Readers can learn about making the form by scrolling back through my last few posts or reading them at my blog:  folkartbycaroljones.blogspot.com
 
The pumpkin was removed from the form in the manner described above, except that I was able remove it in halves rather than quarters.  The larger size of the piece gave it more flexibility.  In the photo above you can see the form is still covered in the Press and Seal.  This is still the same layer of Press and Seal that was used on my first pumpkin.  It is starting to come a loose here and there.  When I use the form again I will probably remove the old Press and Seal and add a new layer of the product.  The old layer feels a little chalky from the flour and is coming loose here and there.

Since taking these photos, I have glued the pumpkin halves back together and added two more layers of paper mâché.  Although I have not done the experiment on the small ball, I used the mortar admix with the flour and water for the paper mâché mixture.  Even if it does not perform as well as I hope, it seems to be working for the paper mâché mixture.  I will be blogging on how this is working out in the next blog post.  Check back in about a week and I will have more information on the experiment and the new pumpkin.

Paper Mâché Pumpkin Part 3- Painting

mâché

Painting is complete.

New readers who may wish to see more on the construction of the pumpkin can scroll back through the last few posts, or visit the blog at folkartbycaroljones.blogspot.com

The yellow exterior coat.  Interior is Tangelo.

I have completed the painting on the paper mâché pumpkin.  The painting was a much bigger undertaking than I had expected.  Part of the time it took to paint the pumpkin was because I decided at the last minute to try an experiment.  Just as I was finishing the form of the pumpkin, I had an idea pop into my head about waterproofing it.  I was not sure it was going to work.  I was even more unsure whether I wanted to experiment on a pumpkin that I had spent so much time building from scratch.  However, curiosity got the better of me and I just had to try. 

Red coat painted over brown coat.

This was constructed from newsprint and a basic flour and water paste. This pumpkin was intended for limited outside use, or use in a sheltered area, and is painted with acrylic paints.  Acrylic paints will fade in prolonged exposure to sunlight.  I would have used exterior grade paints, but Covid-19 is a thing at the moment, and I was not heading to my local hardware store for exterior paint during a pandemic.  I had planned on sealing it with spar varnish, an oil based sealer.  When I started the project, there was some spar varnish in the workroom.  However, my husband was doing some Spring cleaning, and tossed it out.  So, at the moment, the pumpkin has been painted, but not sealed.

Sealed with grout sealer.

The idea that popped into my head was to use grout sealer on the paper mâché pumpkin once the last layer was dry.  I painted it with two coats of the grout sealer.  The grout sealer was slightly milky when it came out of the bottle.  When it dried, I could tell that the pumpkin looked a little darker once the grout sealer was painted on, but you could still easily read the newspaper text.  The interesting thing was that the grout sealer turned the paper mache really hard.  Hard like rock.  Sometimes when the end of a piece of paper does not glue down well I either use some white glue to stick it down, or rip it off if it is not in a critical spot.  However, once the grout sealer was on and dry, a single piece of paper felt like it was made out dried clay.  The piece would not tear off. 

After giving the sealer twenty-four hours to dry between coats, I was ready to paint.  I painted the main body of the pumpkin first.  First, I painted on two coats of medium-body Gesso as a primer.    The interior was pained with a craft paint called Tangelo.  It is a red-orange.  I used a brown acrylic paint for the exterior base coat.  The color was called Nutmeg.  It was browner than Raw Sienna but not as dark as Burnt Umber.  I let that dry for twenty-four hours than painted Cadmium Red Light Hue over the brown.  That red is very transparent.  Twenty-four hours later, I added  a yellow color called Straw.  It was a slightly greenish-yellow.  It also had a lot of white in it to opaque it, so I had to use a very thing coat of that color.  The brown and red coats were painted on with a half-inch bristle brush.  The final two coats were Cadmium Orange Hue.  The yellow and orange coats were painted on using a fan brush. 

The eyes were painted separately from the main portion of the pumpkin.  I had initially tried a different paint scheme for the eyes, but did not like it.  I repainted with two coats of the Gesso Primer and then started painting in the order above.  The difference is that I stopped painting after the Straw color.  The yellow seemed to give the pumpkin a baleful stare.  The red paint showing through did give the appearance of bloodshot eyes.

For the main section of the pumpkin's removable top, the primer and colors are the same as above.  The main difference is in the coloring of the stem.  I had a little trouble getting the stem colors to look like a stem.  I painted it over a couple of times.  I wanted to have a little bit of green at the base of the stem.  My first stem attempt was too green.  My second attempt was still to green.  I painted over most of the green with the Nutmeg, some Straw, a little Raw Sienna, and some more Nutmeg.  I finally found something I could live with, so I stopped there.  I just don't have as much painting ability as I would like.  I muddle through somehow.

The teeth are made from purchased paper clay rather than strip paper mâché.  The stem is paper clay also.  After two coats of the grout sealer and two coats of Gesso, they were painted with a base coat mixture of Titanium White, Raw Sienna, and some Pearlizing Medium.  That mixture helped cover the bright white of the paper clay.  A wash of Raw Sienna was applied after the first coat was dry.  Then the small pits and crevices were filled in with a darker wash of Raw Sienna.  After that was dry, the pits were further enhanced with small dabs of Raw Sienna.

Other than that, there were a few highlights painted on, above and beneath the eyebrows and nose to give them some prominence.  I also painted a few areas depressed areas around the mouth to make them more obvious.  That is about it.

At this point, I am calling the painting done.  I will have to wait until I get some exterior sealer to complete the project.  Soon I hope.  The main problem with exterior sealers is that they tend to have a high odor and need to be used on a well ventilated area.  I will have to use them outside and be able to store the project in a shed for a while.  I will figure something out.

My next project is going to be a different experiment on waterproofing the paper mâché.  There are two or three recipes on the internet, and they work.  The problem I have with them is that they make a big mess.  You need a large bucket, fairly large amounts of supplies, a drill with a paddle for mixing, etc.  My husband has the drill and maybe the paddle, but I would need a dedicated bucket. 

I really don't have to place for making such a mess.  The large amounts made by these recipes are way more than I would be able to work with in the amount of time I have available.  A previous attempt at storing the homemade paper clay was not a success.  It was in a bag in the refrigerator, and it molded very quickly.  I wanted to find something easier to make that can be done in small batches.  I have an idea.  I plan to try it out.   Check back in about a week for more on the new project.