# Will spar varnish hurt plastic?



## Lizzyborden

Working on some paper mâché skulls and wanting to add some deodorant ball or ping pong ball eyes to some of them. Wondering how the spar varnish will react with the plastic. Anyone have any experience with this?


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## Pumpkin5

:jol:Sorry Lizzie, I won't be much help. I use Polyacrylic sealer and I've never had a problem, but I cannot comment intelligently on Spar Varnish.








Poly works great, I used it on my countdown sign and the props I made for Papa VooDoo.....Love the stuff!!!


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## Troll Wizard

_*Depends on what your Spar Varnish is made from. Is it an Alkyd (Oil) based product or a water based. If it is a Alkyd product it may not work as well as using a water based varnish. The water based product won't yellow or patina over time as a Alkyd based product would.

Also your paper mache mixture is also water based (if I'm correct) then a water based product would work better for you and clean up it easier. What Pumpking5 is showing would be a great product for you to use and it's water based and fast drying!

The only disadvantage is that from time to time you will need to retouch it if it is being used outside in the elements. But I'm sure other people on here will have their own ideas on what to use simply because there is now a wide variety of products to choose from.

Your other option is to contact the place where you purchased it, or contact a local paint store, because it's something they sell all the time and can tell you what applications it can be used on!
*_


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## Lizzyborden

It's minwax helmsman I believe. Also believe it's alkyd based as it requires solvent for clean-up. I have no complaints with it as I've used it on several props, but all have been entirely out of paper mâché with no plastic parts. I'm not really that concerned with yellowing as that would only add to the prop. Just don't want to spend a lot of time making some great-looking eyes only to discover that the spar varnish will disfigure the plastic. Will have to do some experimentation.


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## RoxyBlue

Definitely test it first. The MSDS for the Minwax Helmsman solvent-based spar urethane lists a hydrocarbon solvent as a main ingredient, so it could be an issue if applied to plastic. The water-based version has acetone, which can cloud some types of plastic.


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## Troll Wizard

_*Follow up......the Minwax Helmsman is mainly designed for interior/exterior wood products only. It's designed to expand and contract with the temperatures of each season. To be honest, I think I would check with a local craft store to see about what types of sealants they recommend for item and for the plastic parts as well.

Their water based product does contain acetone as Roxy explained. It is used mainly as a fast solvent dryer for the water based product. It should be used in a well vented area, as should the alkyd product. Again, this product is designed to be used on wood. 
*_


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## SPOOKY J

Lizzy I use the helmsman spar urethane with green label all the time. I seal my paper mache pumpkins with it. I have also used it on the deodorant ball eyes I've made. I've never noticed any distortion of the plastic. It does give a glossy wet finish and yellowish hue to the balls. So if you paint the iris go a little brighter with the color as it will change from the spar urethane.


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## Sawtooth Jack

As far as waterproofing paper mâché goes, there is nothing better than spar/marine varnish, especially if your October is a rainy one (yes it does yellow your colors and will deepen over time). Polyurethane works well, but will turn milky in extremely wet environments, as it is a water-based product. If you use the brush on spar varnish, it should be fairly easy to work around the eyes and not really cover them up if you don't want too. As with all waterproofing, any scratch or bump will weaken the coverage, so the occasional touch-up will be needed.

NOTE: If you want to cut down on the shine of any varnish a coat of matte spray will do it, although you need to be careful when applying a spray over something like spar, as too thick a coating all at once will turn white and flake off the slick, oil-based surface. As always, follow any safety precautions on the product labels!


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## Lizzyborden

Thanks SPOOKY J and Sawtooth Jack for the info. We've had lots of rain here and haven't had a chance to test it on plastic. Bought a can of matte spray and will be sure to use thin coats as well.


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