# Styrofoam decoys **URL:** \ **Category:** Factual Questions\ **Created:** [July 1, 2009, 5:06am UTC](https://boards.straightdope.com/t/styrofoam-decoys/501553 "2009-07-01T05:06:05Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![powerjacob](https://avatars.discourse-cdn.com/v4/letter/p/f05b48/32.png) [@powerjacob](https://boards.straightdope.com/u/powerjacob)\ **Post date:** [July 1, 2009, 5:06am UTC](https://boards.straightdope.com/t/styrofoam-decoys/501553/1 "2009-07-01T05:06:05Z")
So. My father wants to make some floating goose decoys out of styrofoam in an attempt to increase the size of their spread for their duck blind in a rice field and to save money on decoys. His concern was that over the period of a hunting season the styrofoam would become waterlogged. I mentioned a styrofoam sealer, but could not quote the name of the product. I have seen this type of sealer on several home improvement/craft shows that you paint on the outside of of the styrofoam and it forms a rock hard surface. The most memorable application of this product came from the Discovery Channel program Monster House. They made an entire Dinosaur from styrofoam and coated it in this stuff to make the outer surface seem like stone (or fossilized bones). So, my question is what is the name of this stuff and would it work for making decoys. I know some people make fake rocks out of it, but that limits my knowledge on the subject. I tried googling it, but I couldn’t get anything satisfactory in the way of a particular product. Help me Teaming Millions. ---
**Author:** ![Fear\_Itself](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/fear_itself/32/19637_2.png) [@Fear\_Itself](https://boards.straightdope.com/u/Fear_Itself)\ **Post date:** [July 1, 2009, 9:54am UTC](https://boards.straightdope.com/t/styrofoam-decoys/501553/2 "2009-07-01T09:54:01Z")
I think your father is incorrect in thinking styrofoam can become waterlogged. True styrofoam is a closed cell foam, so it is [very resistant to absorbing moisture](http://building.dow.com/styrofoam/what.htm): > [@](#): > > In the early 1900s, The Dow Chemical Company invented a process for extruding polystyrene to achieve a closed cell foam that resists moisture. Recognizing its superior insulating properties, buoyancy and “unsinkability,” it was originally adopted in 1942 by the Coast Guard for use in a six-man life raft. If your father was referrring to the expanded styrene bead foam that is made into coffee cups and picnic coolers and [mis-named "Styrofoam](http://craft.dow.com/about/cup.htm)", it is still [unlikely it could become waterlogged](http://www.texasfoam.com/technical-data.htm): > [@](#): > > The cellular structure of Expanded Polystyrene is essentially water resistant and provides zero capillarity. However, Expanded Polystyrene may absorb moisture when it is completely immersed, due to the fine interstitial channels between the molded beads. While molded Expanded Polystyrene is nearly impervious to liquid water, it is moderately permeable to water vapor under pressure differentials. Vapor permeability is determined by both density and thickness. Generally, neither water nor water vapors affect the mechanical properties of Expanded Polystyrene. ---
**Author:** ![GaryM](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/garym/32/241_2.png) [@GaryM](https://boards.straightdope.com/u/GaryM)\ **Post date:** [July 1, 2009, 12:40pm UTC](https://boards.straightdope.com/t/styrofoam-decoys/501553/3 "2009-07-01T12:40:26Z")
In any case, epoxy is usually safe for use on foam. Not to be confused with polyester resin which is not. ---
**Author:** ![powerjacob](https://avatars.discourse-cdn.com/v4/letter/p/f05b48/32.png) [@powerjacob](https://boards.straightdope.com/u/powerjacob)\ **Post date:** [July 3, 2009, 5:19am UTC](https://boards.straightdope.com/t/styrofoam-decoys/501553/4 "2009-07-03T05:19:40Z")
> [@GaryM](#): > > In any case, epoxy is usually safe for use on foam. Not to be confused with polyester resin which is not. Gary, thank you for your post. Unlike Fear Itself your answer is more helpful. Yes I know that styrofoam does not get waterlogged in the sense that something like wood. If my father wanted he could take a huge chunk of foam from his camp and make the decoys, but, since it has been sitting under a floating walkway for a couple of years it has taken on water. It still floats, but a twenty five pound block of styrofoam now weighs considerably more due to the constant exposure to water (hence the term waterlogged). The stuff I’m looking for is especially made for styrofoam. It is an epoxy, but I don’t know what to actually look for. If you or anyone else can help me in the matter I would greatly appreciate it. I want to say the stuff starts with a “V”, but I cannot be entirely sure. Any help in what I’m searching? ---
**Author:** ![Dewey\_Finn](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dewey_finn/32/4222_2.png) [@Dewey\_Finn](https://boards.straightdope.com/u/Dewey_Finn)\ **Post date:** [July 3, 2009, 6:19am UTC](https://boards.straightdope.com/t/styrofoam-decoys/501553/5 "2009-07-03T06:19:41Z")
[Vanillacryl](http://www.fxsupply.com/vanillacryl/vanillacryl.html), perhaps? ---
**Author:** ![JFLuvly](https://avatars.discourse-cdn.com/v4/letter/j/ac91a4/32.png) [@JFLuvly](https://boards.straightdope.com/u/JFLuvly)\ **Post date:** [July 3, 2009, 2:33pm UTC](https://boards.straightdope.com/t/styrofoam-decoys/501553/6 "2009-07-03T14:33:10Z")
Google styrofoam lobster buoy paint, that should be what you’re looking for. I would think that some paints would eat the styrofoam. ---
**Author:** ![GaryM](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/garym/32/241_2.png) [@GaryM](https://boards.straightdope.com/u/GaryM)\ **Post date:** [July 3, 2009, 6:54pm UTC](https://boards.straightdope.com/t/styrofoam-decoys/501553/7 "2009-07-03T18:54:14Z")
True some paints will eat Styrofoam. But Krylon makes some paints specifically for plastics, don’t know off hand if foam is included in the types it’s good for. But foams cheap so it should be easy to find out. When I was into building RC sailplanes, we’d hot wire foam wings out of white or blue foam and laminate either balsa skins, or layup wet glass cloth skins. We always use “West Systems” epoxy. Came in two one-gallon cans with a metering pump on top. Just use the same number of pumps from each can. Worked great. Any well equipped boating supply store should have it. ---
**Author:** ![CalMeacham](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/calmeacham/32/35_2.png) [@CalMeacham](https://boards.straightdope.com/u/CalMeacham)\ **Post date:** [July 3, 2009, 7:29pm UTC](https://boards.straightdope.com/t/styrofoam-decoys/501553/8 "2009-07-03T19:29:30Z")
I suspect that if you made a decoy out of the coffee cup-type Styrofoam it would float too high out of the water and look fake. It might even tip over in the wind, unless you ballasted it.