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Discussion Starter · #1 ·
I'm in the middle of making a new background, and wanted to try the concrete method. I've been reading the posts, using the search, but am still unclear on a few points:

1) Can I use a plain bag of quickrete cement and supplement with the binder, or are the best results from the underlayment cement?

2) In the application, I know that most people do multiple coats, a little thicker each time. I'm unclear as to how long to wait between coats? Am I looking for the previous coat to be completely dry, or just to the point of setting, before applying the next coat?

3) In the leeching/curing process, is there a major time difference when spraying the concrete vs submerging the entire background? Also, is the GS Foam OK to be submerged with the concrete?


Thanks guys
 

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1. I used a dedicated product, specific for sealing drinking water reservoirs, pools and "wet rooms". It came in a bag and a bottle. In the bag was the powdered part, both concrete and some dry polymers (so it said on the bag) and the bottle had polymeric binder in it.
The product i used was called "Hydroseal 2 part elastic concrete" though while researching i found many other generic names for it.

2. I waited until each coat was completely dry, which took between 24-48 hours for each coat, depending on the thickness of it. Looking back i know i used too much concrete in each of the layers, because i used 3 or 4 layers and ended up covering a lot of detail i carved in the styrofoam. More over, these products are effective after a single decent coat for drinking water porpuses, so 3 coats that cover the whole stucture are enough in my opinion - no need to bulk things up with thick concrete globs.

3. I wondered the same thing while doing my project, and contacted a relative of mine who works as a building engineer. He said that when a company wants to test the strength of the concrete they submerge a block of it for 72 hours, to get the best result strength-wise (via the process of hydration of the concrete. submerging the concrete ensures that there will be enough water for the concrete to bind). That said, he added that submerging does not have any real advantage compared to spraying in background-construction related applications, and after a week with a couple of sprayings a day it should be fully hydrated, neutral and ready for painting, with water-resistant non toxic acrylic paint, of course.
Covering the background with a plastic sheet or a nylon bag prevents the sprayed water from evaporating, so it lessens the amount of sprayings needed.

Hope i helped,
Almog
 

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Discussion Starter · #5 ·
ok, so grout as in tile grout? I'm kinda limited in suppliers in my area, so my first choice is Lowes. Could somebody please recommend an actual brand from lowes, be it either floor underlayment or grout? Is the process the same for both? The wife was shopping at Lowes over the weekend and asked for the underlayment cement, and the Lowes employee gave her a bag of quickrete and bonder, which I knew wasn't right, so now I try to go in knowing exactly what I need.

Thanks again
 

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Discussion Starter · #7 ·
I ended up going with the Henry 549 Underlayment patch/skimcoat. I've read the few threads the search function brought up, but am still unsure if I need to seal this, or just cure and leach?

Thanks again for all the help
 
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