# HELP! My concrete won't stick to my foam... WTF???



## iheartmycichlids (Mar 10, 2009)

Ok, I've finished carving my background and mixed up the quikrete really thin so it would just coat the foam, but it won't stick. THe I tried it thick, and that didn't work. Has anyone else had this problem?? What do I do?? I worked really hard on this background and now I can't coat it?? HELP!

This is what I'm using


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## Stickzula (Sep 14, 2007)

try adding acrylic fortifier to the mix. You don't want it too thin or too thick. Think a partially melted milk shake.


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## tommy022060 (May 1, 2008)

I used quikrete hydraulic cement


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## garett1020 (Apr 8, 2009)

tommy022060 said:


> I used quikrete hydraulic cement


me too.....good stuff


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## dreday (Oct 12, 2007)

yea the acrylic fortifier helps cure fast and make it durable under water.

the trick to get it to stick is to rough up the stryo. use some heat. either a hair dryer or a blow torch(really really lightly and quickly) to melt the top a little and give it some more texture. and you want the cement to be like a thin milkshake. but if you have some cement on there already keep working with that.

just keep adding layers until you have a good start. then make a think mix and add it on. but not so thick as it will clump. it should still be soupy.

you need to get it going before it will stick. more layers or melting should help. make sure you let the layers dry a day or two first.


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## Rick_Lindsey (Aug 26, 2002)

My first thin layers of styro beaded up, I mixed some a touch thicker and just kept adding layers.

-Rick (the armchair aquarist, who was using mortar mix)


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## Mcdaphnia (Dec 16, 2003)

Be sure you have a mortar mix, not a stone aggregate mix. Follow manufacturer directions as to how much water. Don't make soup or any other suggestion. Concrete does not stick well to styrofoam. Making it wetter and weaker will not help in the long run. Wind nylon yarn around the foam and using a knitting needle, fasten it where you can't wind it around. Lay the background on its back and apply the concrete where it will stick. Don't worry about 100% coverage. A second layer should connect the dots. I would use the acrylic fortifier because it makes the concrete smell better while you are working with it. That is enough reason to use it for me, but it should also make it hold on in thinner layers than plain concrete. It probably also seals in some of the chemicals that will gradually make the concrete strong when protected from being leached out. If they do leach out, they can raise th pH too high for fish comfort.


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## BinaryWhisper (May 5, 2006)

mortar mix with acrylic fortifier and paint on a thin coat to begin with. I use a stucco brush for the first coat.


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## iheartmycichlids (Mar 10, 2009)

THANK YOU!!! Everyone! This seems to be working great!! THANKS!!!  :fish: =D>


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## kumargovind (Aug 6, 2020)

hey, this is govind. currently developing a mould made out of polystyrene and need more info on if i can use builders bog on the polystyrene as well. Got the understanding on how to use cement mix and plesase help me to replicate the same results with builders bog. 
thanks in advance guys. Am new to this hope i find great advice from you guys. Cheers and stay safe in such times


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## kumargovind (Aug 6, 2020)

iheartmycichlids said:


> THANK YOU!!! Everyone! This seems to be working great!! THANKS!!!  :fish: =D>


Hey mate, good to know it worked for you. Please tel me if the foam was stable and did not deteriorate after some time. Thanks


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## Deeda (Oct 12, 2012)

Govind. what is builders bog? The only reference I can find is it's used as a repair material to fill in wood for wood workers and painters.


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## kumargovind (Aug 6, 2020)

Hey DeeDA, You are appsolutely right about it. However, to impart strength to polystyrene, my team mate selected builders bog as hardeniong material. So i was lead into that direction and trying to find ways in which bog correctly fits on the foam. (Hoping to use Turbo builders bog from bunnings)


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## Deeda (Oct 12, 2012)

You might want to contact the Mfg. to see if the product is suitable for use with polystyrene plus underwater permanently and if the cured product is safe for aquarium use. You may not get an answer as to the last question as many Mfg.'s don't test for aquarium use of building materials.


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## kumargovind (Aug 6, 2020)

Deeda said:


> You might want to contact the Mfg. to see if the product is suitable for use with polystyrene plus underwater permanently and if the cured product is safe for aquarium use. You may not get an answer as to the last question as many Mfg.'s don't test for aquarium use of building materials.


Thanks for the info i would definetly do that. Cheers


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