# Need to carve great stuff?



## Mavpa (Jan 5, 2015)

I've got a pretty good size background I built up with great stuff and am going to be covering with Spyra... my question is, do I need to cut/sand the great stuff to get past that little outer shell for any reason, or can I just glue the Spyra right on top of the outer layer?


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## thane (Sep 11, 2014)

I'm doing my first great stuff background right now. I have read several people say that if you're going to stick silicone over the great stuff (then you stick coco fiber to the silicone), you have to rough up the great stuff first to remove the "shiny" surface, or the silicone won't stick. I don't know if you're intending to use silicone or just glue, but my guess is you might want to do the same just in case the glue won't stick. I tried different tools and found a plain serrated steak knife worked best for removing larger portions of great stuff. Then I used a Dremel tool with a burr bit to carve out some finer detail.

Good luck,
Thane


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## cmk (Aug 29, 2014)

Yep cut it, sand it, pull pieces off. I use 2 steak knives one straight and one bent 90 degrees to add detail.


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## tardis101 (Apr 11, 2012)

I've done four great stuff tanks now (two 29 gallons, one 55 gal, and one 90 gal. I haven't seen nor had any of the silicon caulk come off and I don't rough it up at all. But I have noticed on areas that were particularly smooth the coco fiber can brush off if you poke at it. On those spots I just dab a little more caulk and then stick on some dry moss. If I had to guess I would think you'd get a little better results with roughing it up if you aren't using caulk.


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## chin_monster (Mar 12, 2006)

The easiest way I found to de-skin spray foam (great stuff) is to go at it with rasping bit in a dremel or regular drill. 

It'll make the biggest mess you can imagine but sure beats trying to do so with a knife.


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## SwampMan (Jun 26, 2015)

I recall seeing a video where wood glue was being used instead of silicone to prevent sloughing.


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## Mavpa (Jan 5, 2015)

For the Spyra, I was just going to brush on Gorilla glue. I'm not using silicone.

By biggest concern is that I know plants can root into great stuff because the foam is permeable enough, I just don't know if to get to that point, you need to cut that outer skin off.

I'm probably just gonna bust out the old "hot wire cutter" and see if it can give it a quick shave.


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