# Great Stuff Experiment - Is There Anything GS Won't Stick To??



## Bob Hall

While searching through and reading threads about using Great Stuff, I ran across an older topic where someone asked the question, "is there anything Great Stuff won't stick to?" There were a few suggestions, including parchment paper, non-stick spray-coated aluminum foil, and plastic wrap. A few popped in and said "it won't stick to ...." Since I want to do at least some of my build outside the enclosure to be added later, I had asked myself the same thing. A lot of you probably already know the answer, but for those of you who may be like me and unsure, here's my little contribution.

First I covered a piece of cardboard with plastic wrap, pulling it tight and taping it in the back with packing tape.


Now it's time to spray on some "rocks." I included the following photo as sage advice. See that wimpy-looking blue thing on my hand? It's called a glove. Use gloves. One thing I discovered years ago was that *GS DOES STICK TO SKIN!* ..and I never discovered anything that will take it off short of just wearing it off.


So, back to the rocks. I sprayed four little piles of GS. I figured that would be a better test than just one. It is amazing how fast those cans empty. I'm pretty sure there's less than a third of a can left after making my little piles.


Confession time. I waited about 2 hours and had to peek. The outside was cured fairly hard but when I pulled one up the bottom was wet. There was GS stuck to the plastic too. After seeing the mess under the one I pulled up I figured, at a bare minimum, I was going to have some residue left for that one even after waiting overnight. I poked it back down, turned the lights off, and went to bed.

The next morning I was surprised to see that the GS piles were even bigger than when I left them the night before. Keep that in mind....the foam continues to expand a bit even after it's partially cured.


'Acid test' time. I start with the one I'd pulled up early the day before. To my surprise, it peeled away clean. The other three were the same...they peeled away from the plastic with no apparent residue.


If you look closely at the bottom of the pile I'm holding you'll notice that, under the hard skim coat, the GS appears to remain tacky even after curing overnight. That's something to keep in mind if you plan to carve the 'rocks', as I do. I can see myself hacking into one and getting GS all over my hands after being so careful to wear gloves in the beginning.

So there you have it....at least one thing Great Stuff won't stick to. I'm out of parchment paper so, when I do have some, I'll try that and add an update.

Hope this helps someone!


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## Mohlerbear

That's a good idea. I normally would spray it onto whatever and try to saw it off, leaving GS behind and ultimately wasting some. Thanks for the tip!


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## Judy S

I've used the extra large black plastic bags...not that size matters in this context....and if you use pins, whatever...to poke the blobs, it gets air into the blob and it cures faster...you can also poke a gloved finger and sort of shove it around into some interesting shapes...


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## Bob Hall

Judy S said:


> I've used the extra large black plastic bags...not that size matters in this context....and if you use pins, whatever...to poke the blobs, it gets air into the blob and it cures faster...you can also poke a gloved finger and sort of shove it around into some interesting shapes...


Good idea! After 48 hours mine were cured, but deeper piles may take longer. Thanks for sharing!


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## Aldross

Going to try and make some ledges this weekend with the cling wrap method. How do you intend to color them? Drylock maybe. I want mine to look like rock so I was thinking maybe grout then seal them.


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## Bob Hall

Aldross said:


> Going to try and make some ledges this weekend with the cling wrap method. How do you intend to color them? Drylock maybe. I want mine to look like rock so I was thinking maybe grout then seal them.


I'm trying to create lots of layers, similar to a sedimentary outcropping, so I'll first slice those piles into thin layers then shape, stack, and glue them with Gorilla glue. I'll use zoopoxy to coat the GS, then add some tints and highlights with thinned acrylic paint. I've got a 'first build journal' going so I'll probably detail what I try there, when I get to that point.


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## Judy S

since Gorilla Glue is the same chemical composition as Great Stuff...it naturally sticks to each other...and the GG can be mixed with different, even organic, things...water is an activator for either...


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## Aldross

Judy S said:


> since Gorilla Glue is the same chemical composition as Great Stuff...it naturally sticks to each other...and the GG can be mixed with different, even organic, things...water is an activator for either...


I have yet to use gorilla glue. How much does it expand? Enough to distort the shape of something carved i'm guessing.


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## Bob Hall

Aldross said:


> I have yet to use gorilla glue. How much does it expand? Enough to distort the shape of something carved i'm guessing.


I plan to do most of my shaping before gluing it all together. When I do glue it I'll weigh it down with something until it sets, then clean up any glue that oozes out. The great thing about emulating natural things is it's already organic in shape....a little heave here and there will probably add to the reality of it. A lot of this is guessing since I've never done it. I'll know more soon.


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## Judy S

GG does ooze a bit...but it is more dense than the GS and spritzing it with water really accelerates the set.


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## Bob Hall

*Re: Great Stuff Experiment - UPDATE*

As promised I tried a couple of other materials to see if Great Stuff would stick to it.... parchment paper and a black garbage bag. It stuck to neither of them, but I made a nice discovery. In both the plastic wrap and the garbage bag the bottom of the 'blob' took overnight to cure. When I used the parchment paper the entire 'blob' cured in a couple of hours. Since it cured much faster I was able to make several rounds of spraying in one evening with the same piece of parchment paper...so that's what I'll be using from now on. I'm guessing it is because the parchment paper is more porous, allowing air to reach the bottom as well. Either way, IMHO, that's the way to go!


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## Benji

Can't wait to see the finished products once you carve them down and zoopoxy them. Has the zoopoxy come in the mail yet?


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## Bob Hall

Benji said:


> Can't wait to see the finished products once you carve them down and zoopoxy them. Has the zoopoxy come in the mail yet?


Should be here this week. I'm excited about trying it. I do need to get all those piles of GS cut down and shaped as well...maybe a New Year's Day project.


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## frogfreak

Hey Bob,

Misting the larger pieces should speed up cure time too.

*For large voids, mist water between foam applications to speed curing.*

How To Use GREAT STUFF? Foam | Spray Foam Insulation Safety

The parchment paper idea is cool!


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## Joe S

I love what you are doing, here is another thing it wont stick too....well.

eariler this year I was making large box pond type enclosures out of extruded polystyrene, the massive sheets of insulation foam. Due to the foam having a slick heat sealed surface it also wont stick to that sadly. 

Keep up the good work.


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## Bob Hall

Joe S said:


> I love what you are doing, here is another thing it wont stick too....well.
> 
> eariler this year I was making large box pond type enclosures out of extruded polystyrene, the massive sheets of insulation foam. Due to the foam having a slick heat sealed surface it also wont stick to that sadly.
> 
> Keep up the good work.


Ah, a case of wanting it to stick but it won't. Good to know! I wonder if you can peal that heat shield off without a lot of grief? Thanks for the tip!


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## Bob Hall

frogfreak said:


> Hey Bob,
> 
> Misting the larger pieces should speed up cure time too.
> 
> *For large voids, mist water between foam applications to speed curing.*
> 
> How To Use GREAT STUFF? Foam | Spray Foam Insulation Safety
> 
> The parchment paper idea is cool!


Judy had said that moisture is the activator...didn't think of spraying it though. Thanks for the tip!


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## rxrestorer

Saran or plastic wrap, just need to wait for it dry thoroughly before removing. Try to keep the foam thinner rather than building large bulky items


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