?? Casting Flexible Mold with MarcoRocks Mortar Mix

[rhizotron]

I'm wondering about an alternative application for E-Marco-400 Aquascaping Mortar Mix and I hope somebody who has experience with it might care to comment. I need to cast a shape for a special marine tank feature using a flexible mold and I wonder how well the mortar will hold up as a larger form and if I can hope to get it into the mold. The mold is open on one side, so my plan is to just press the wet mortar into the finer mold features.

I'm going to need some volume to fill the mold cavity, so for sake of economy I also wonder about cutting with fine aragonite sand maybe in a 1:1 ratio. The feature does not need to support any additional weight, but it does need to last.

I would just cast with a Portland cement concrete mix, but it sounds as though E-Marco-400 will be a more reliable for long-term durability. And it's offered in white, the preferred color for this project.

Any opinions? How about ideas for other products to achieve this?

 

[ISpeakForTheSeas]

I've leave comments on your idea up to others with more experience in this field, but for other ideas:

The best way might depend on what you're trying to do with the aquascape, but here are some ways that have been used successfully for various scapes/kinds of scapes:

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[delv2323]

Go to Smooth-On and get the correct product. Luckily, this sounds like a standard project, why try to reinvent the wheel?

 

[rhizotron]

I've leave comments on your idea up to others with more experience in this field, but for other ideas:

Thanks! Bookmarked.

Go to Smooth-On and get the correct product. Luckily, this sounds like a standard project, why try to reinvent the wheel?

As far as I can see Smooth-On doesn't offer concrete products for casting. Most of their offeringss are either for flexible molds or casting with resins or foams.

 

[delv2323]

Maybe I don't understand, why do you want to make a mold out of concrete? It's heavy and unwieldy.

 

[twentyleagues]

I've used portland cement mixed with crushed oyster shell and other shells to make agracrete before. I used a sand mold when I did it. Water softener salt to make it porous. It takes some trying to get it right start small. 4-6 weeks in a tub of water to disolve salt and leach concrete. Water changes every couple of days. I dont think marco-400 would be a good medium. I used a very small bit of that before. I dont know all the ins and outs of the marco though may be able to water it down to get a soupy consistency to apply the first couple layers in the mold to get all the detail not sure just spit balling.

 

[rhizotron]

Maybe I don't understand, why do you want to make a mold out of concrete? It's heavy and unwieldy.

The mold is not going to be concrete. A mold is the negative shape of the form you want to make and it is usually a flexible material. The cast is the usually rigid thing you make by pouring concrete, resin or other material that sets up hard into the mold.

I've used portland cement mixed with crushed oyster shell and other shells to make agracrete before. I used a sand mold when I did it. Water softener salt to make it porous. It takes some trying to get it right start small. 4-6 weeks in a tub of water to disolve salt and leach concrete. Water changes every couple of days. I dont think marco-400 would be a good medium. I used a very small bit of that before. I dont know all the ins and outs of the marco though may be able to water it down to get a soupy consistency to apply the first couple layers in the mold to get all the detail not sure just spit balling.

Yes I'l probably just use a Portland cement option. I just wondered about the Marcorocks because it's proven for strength in saltwater and because it's white. I suppose what I really wondered was about thinning it enough to make it pourable or easily pressed into a mold. But it's configured as a mortar and I can imagine that might not work.

White Portland cement is available. And I also wonder about polymer additives for submerged saltwater applications(?).

https://difepitiles.com/products/white-portland-cement-type-i-for-molds-and-casting

 

[twentyleagues]

The mold is not going to be concrete. A mold is the negative shape of the form you want to make and it is usually a flexible material. The cast is the usually rigid thing you make by pouring concrete, resin or other material that sets up hard into the mold.



Yes I'l probably just use a Portland cement option. I just wondered about the Marcorocks because it's proven for strength in saltwater and because it's white. I suppose what I really wondered was about thinning it enough to make it pourable or easily pressed into a mold. But it's configured as a mortar and I can imagine that might not work.

White Portland cement is available. And I also wonder about polymer additives for submerged saltwater applications(?).

https://difepitiles.com/products/white-portland-cement-type-i-for-molds-and-casting

oh yeah I used the liquid polymer too. Its been so long since I did it. I was thinking the same on the marco.