Like water off a paper mache ducks back

Sawtooth Jack · #1 04-26-2011

Okay Paper Mache experts. I tried to find a relevant thread, but couldn't find the answers, so here are my questions:

1) When waterproofing paper mache, is marine varnish any better than spar varnish? I know marine is more expensive, but wondered if it was worth the extra cost per gallon.

2) Also do you recommend putting on a coat of varnish before you paint as well as after you paint, or is that overkill?

RoxyBlue · #2 04-26-2011

Stolloween is the man with the answers for this one

I don't use marine or spar varnish on my mache projects since they are not expected to be exposed to weather for any length of time. I do use a sealant (not varnish) before painting so the mache won't get soggy, then use a varnish (the kind you get at Michaels or a craft store) after painting to protect the surface.

Sawtooth Jack · #3 04-26-2011

Wow, for all of my watching bits of my project cave in while adding layers, I didn't think about that happening while painting! You just saved my from some future heartache I'm sure!

I've read quite a bit about technique on Stolloween's blog. Between him and few others I've cobbled together a technique that seems to be working for me so far (fingers crossed). I just figured it would be good to pick a few more brains while I'm still working toward the paint stage.

Thanks!

MacabreRob · #4 04-26-2011

Dryloc works good too.

STOLLOWEEN · #5 04-27-2011

According to "The Papier Mache Resource" the best sealant for papier mache is marine varnish, after some research I found that marine varnish ran about $90 per gallon...with that said I've never used it. I use spar urethane to seal my props, here's a definition of the product.

Spar Urethane is a protective clear coat finish that has been specially formulated to use on interior or exterior wood surfaces exposed to water, sunlight, or changes in temperature. The UV blockers contained in Spar Varnish, help to reduce the effects of fading or graying caused by the sun.
The basic difference between other varnishes and spar, is the ratio of oil to resin. In spar, this ratio is relatively high, which makes for a more flexible finish. It is tougher than polyurethane, making it more resistant to cracking and chipping. This also makes it more durable under dramatic temperature changes

Spar Urethane has done a good job protecting my props from water and humidity...note that I do NOT use the water based Spar Urethane...I've found from past experience that water based sealants do not perform as well as the non-water based sealants. Also note that my props are only displayed for several days during the Halloween season, five days is the max and I tend to babysit my props meaning that if it is down pouring I will protect my props either by removing or covering. Last summer I did an experiment and left a papier mache pumpkin outside for over 100 days, a pumpkin coated in Minwax Gallon Helmsman Spar Urethane VOC Semi-Gloss and it came away without any noticeable water damage. The fumes from this product are nasty so be sure to use outside and stay down wind...just a little inhalation can give you a bad headache and sore throat.

Here is a link to the pumpkin experiement:
http://www.stolloween.com/?page_id=4217

Hope this helps.

Scott

Dixie · #6 04-27-2011

Just can't beat that answer, can ya? I love Hauntforum, LOL!

niblique71 · #7 04-28-2011

Quote:

Originally Posted by STOLLOWEEN

According to "The Papier Mache Resource" the best sealant for papier mache is marine varnish, after some research I found that marine varnish ran about $90 per gallon...with that said I've never used it. I use spar urethane to seal my props, here's a definition of the product.

Spar Urethane is a protective clear coat finish that has been specially formulated to use on interior or exterior wood surfaces exposed to water, sunlight, or changes in temperature. The UV blockers contained in Spar Varnish, help to reduce the effects of fading or graying caused by the sun.
The basic difference between other varnishes and spar, is the ratio of oil to resin. In spar, this ratio is relatively high, which makes for a more flexible finish. It is tougher than polyurethane, making it more resistant to cracking and chipping. This also makes it more durable under dramatic temperature changes

Spar Urethane has done a good job protecting my props from water and humidity...note that I do NOT use the water based Spar Urethane...I've found from past experience that water based sealants do not perform as well as the non-water based sealants. Also note that my props are only displayed for several days during the Halloween season, five days is the max and I tend to babysit my props meaning that if it is down pouring I will protect my props either by removing or covering. Last summer I did an experiment and left a papier mache pumpkin outside for over 100 days, a pumpkin coated in Minwax Gallon Helmsman Spar Urethane VOC Semi-Gloss and it came away without any noticeable water damage. The fumes from this product are nasty so be sure to use outside and stay down wind...just a little inhalation can give you a bad headache and sore throat.

Here is a link to the pumpkin experiement:
http://www.stolloween.com/?page_id=4217

Hope this helps.

Scott

Wow that certainly was an impressive result. Charlie seemed to make it through the weather just fine. My props are outside for at least 30 days and many of them are in wooded areas with leaves etc. I wonder if this sealing technique would also protect mache' projects in direct contact with the ground?? I'm still very skeptical that mine would survive more than a few seasons, but you can't argue with your results.

Thanks for volunteering Charlie for this experiment, he didn't seem to mind.

Sawtooth Jack · #8 04-28-2011

Thank you Stolloween!

I saw your blog post about "Charlie" and was intrigued by the spar urethane on mache (most paper mache folks just said to avoid outside entirely or expect mush). I did see quite a difference in cost (over $40) per gallon between the Spar urethane and the Marine varnish at the hardware stores around here, so it looks like I'll be experimenting with Spar urethane for my props, and thanks for pointing out the oil-based requirement. My store-bought display sat out all month, but the props I'm making for myself this year should only have to live through a week or so of exposure to the elements.

Dixie, you said it! That's why I came out here!

Thanks all for the terrific advice. Looking forward to that final protective coat with some confidence now!

STOLLOWEEN · #9 04-28-2011

I use a variety of techniques so that none of my papier mache pieces sit directly on the ground, if you look at the picture all the pieces that appear to be sitting on the ground are actually on wood pallets that have been painted black and covered with leaves.

Sawtooth Jack · #10 04-28-2011

Thanks again! I have been thinking about putting foam or something on the bottom of my props to keep the constant wet off their undersides, but haven't devised a plan for that yet, as my props (when built!) will be of varying shapes and sizes. The idea of using a paltform is a great idea, plus it would add to my now limited decor.