Thursday, July 23, 2009

Q&A: Weather Proofing

Questions regarding my projects and papier mache regularly fill my mailbox. In an effort to answer these questions and share information some of these questions will be regularly featured on this blog.

Johnny wrote:

“ If you could tolerate being asked advice for probably the hundredth time on the same topic:

This is the first time I'll use paper mache props in my haunt and they'll be outside for the whole month of October. We'll typically have 1 or 2 rains during that time. Temperatures may vary from 30 to 80 degrees during the month; btw I'm in southeast Mississippi.

I'm doing strip mache with a water/liquid starch mix. Everything gets at least two coats of exterior enamel before the detailing.

What are the chances my props will hold up to the elements for a month, or should I protect them more when not in use? “

Protecting papier mache from the elements is probably the most frequently asked question.

Exterior paints whether latex or enamel provides the first level of protection against moisture but paint alone is not enough. All papier mache that is going to be used outdoors needs a coat of sealant in order to withstand moisture from not only rain but also humidity. Basically any product designed to seal wood will work on papier mache. Products such as spar urethane, polyurethane, varnish and shellac work.

A few things to remember:

1. Most sealants have a glossy finish which may not be desirable for many props. Who wants shiny tombstones? The solution is to seal the papier mache before painting, this way the paper is protected and the paint will cover the gloss.

2. Cover all surfaces. Sealants only work if all exposed papier mache surfaces are thoroughly covered. If you have created something that is hollow such as a skull or pumpkin take the time to seal the interior because unsealed papier mache whether strips or clay will absorb moisture.

3. You get what you pay for. From my experience I have found that cheap or inexpensive sealants do not protect as well as more expensive products. My preferred sealant is Spar Urethane which costs about $30 per gallon. Here is some more info on Spar Urethane.

4. Read the warning label. Most sealants produce harsh, flammable and toxic fumes. Follow the manufacturers guidelines and use only in well ventilated areas with the proper safety gear.

5. If your props do become soft from moisture don’t panic, simply place them in front of a fan in a dry environment and they will come back to their former glory.

My papier mache props are only displayed for about a week before Halloween and during this time I really pay attention to the weather.

Living in Michigan we get every imaginable weather condition during October including extreme heat, wind, rain, hail and have even had snow accumulation. The best advice is to use common sense, if you know it’s going to downpour then make the effort to move your props to a safe place or cover them.

Papier mache is surprising durable but take measures to prevent them from being exposed to harsh elements.

Here is an additional link to an article published last year.

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