Things You'll Need
Paper-mache is the ultimate all-purpose craft medium because it can be used to create artistic sculptures, to make decorative bowls and holiday ornaments and even to complete school projects. All that is needed to make paper-mache is flour, water and paper. While making paper-mache projects may be easy, sometimes it is difficult to keep projects from becoming moldy as they dry. Paper-mache is very moist and this moisture is the perfect place for mold to grow. By adding salt to your paste and by taking a few precautions, you can prevent your paper-mache projects from molding.
How to Make Mold-Resistant Paste
Pour some plain white flour into a bowl. The amount of flour does not need to be measured because the amount of water you use will vary depending on the desired consistency for your paste.
Add 1 tbsp. of water at a time, mixing the paste with a wooden spoon or an electric mixer. A wooden spoon will be sufficient until the mixture becomes more liquid -- then you will need an electric mixer to smooth out any lumps.
Continue to add water, mixing thoroughly, until your paste reaches the desired consistency. If you want a thicker paste, add water until the mixture reaches the consistency of pancake batter. If you prefer to work with thinner paste, keep adding water until the mixture becomes very runny and almost resembles watered-down milk.
Add 1/2 tbsp. of salt for every cup of flour used in the paste and mix it in well. The salt should help to prevent mold as your paper-mache dries because it will suck up some of the extra moisture.
How to Keep Paper Mache Sculptures from Molding
Squeeze as much excess water from your paper-mache pulp as you can before you begin your sculpture.
Place drying sculptures in a warm oven (no hotter than 200 degrees Fahrenheit) or near a heater or radiator. The heat will help moisture to evaporate more quickly and the sculpture should dry well without molding.
Allow the sculpture to dry completely before adding any paint or finish. If the paper-mache is still damp when a layer of paint is applied, the sculpture may begin to mold from the inside layers out.
If you live in a humid area, you may want to place your sculpture in front of a fan as it dries so that the moisture in the air is not given an opportunity to settle onto the sculpture.
It is possible to use wallpaper pastes that contain fungicides for paper-mache, but this option is much more expensive. Also, these products contain poisons to prevent the growth of fungus and may not be safe for use by children.