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Failure and frustration - ideas/solutions please

Posted by curbdiver1954 (My Page) on
Sat, Aug 23, 08 at 18:09

Finished a gazing ball a few weeks ago that my sis fell in love with, but it needed a sturdy stand due to the strong winds in her area. Decided I wanted to use a green glass vase as the stand part, so I made a stepping stone to mosaic. Got a bag of "Type S portland mortar mix" which the guy at HD said was the same as Portland cement ( it is composed of sand and Portland cement). Used a greased cake pan for the mold and poured a layer about 1" thick, let it cure for a couple of weeks, poured a second layer of same thickness and centered the top of the vase in it so the mix came up the inside and outside of the vase to hold it in place. Unmolded it today after it had set for a week. Found 2 problems and don't know what caused them:
1. Two vertical cracks in the second layer that started at the juncture with the bottom layer and went to the top of the 2nd layer. Cause??
2. Even after letting it set, I can easily sand all parts (sides, top and bottom) of the stepping stone with a piece of 150 grit sand paper. Cause??

A few taps with a hammer and that 2nd layer just fractured and came off the bottom layer, leaving the piece that was inside the vase relatively intact but with cracks all over it. Vase is still intact so I can still use it to make a stand, but I'm really frustrated about the failure of the layers to stick together, the ease of sanding it and the cracks.

Ideas on what caused the problems?? How I can avoid them on future stones??

Thanx!
Pat


Follow-Up Postings:

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RE: Failure and frustration - ideas/solutions please

Need to spritz the first layer first b/f putting on another. The cracks might not have occurred had you put in some structural support - chicken wire or the wire mesh. Know you must be VERY frustrated - don't stop - keep experimenting.


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RE: Failure and frustration - ideas/solutions please

I can't offer any advice Pat but I just wanted to say I was sorry it didn't work out for you. At least you can reuse the vase and attempt to do it again somehow. Slow's advice makes sense to me...hope it works out for you.

Barb


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RE: Failure and frustration - ideas/solutions please

Pat, so sorry about your project, I know you must be down, I can't offer any advice but to chalk it up to experience

I think you should follow Slow's advice and try again using wire mesh or chicken wire. , At least you still have the vase so you can try again.
I would really like to try that somtiime, bought the portland cement and some sand.. just can't get up the nerve yet. I've just been using the really smooth ready made mix and I have enough to make one more.

then i will try what you are doing.

Please let us know what you decide, and know I have, and probably most of this list, been there, and that's how we learn.

Good LUck


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RE: Failure and frustration - ideas/solutions please

Two questions come immediately to mind: Why did you do it in two layers, and why did you leave it set so long between pours? I'd put something in the mold to hold the vase at the level you want (probably rocks, or chicken wire or mesh armature)and pour it all the same day. POUR the first half, set in your vase, then pour the rest around it. I've used tape lots of times to hold something in place until it was set (whether it was set in silicone or thinset, works either way, as would in concrete). As long as it cured, no way it should sand off though. Your portland may have been bad. Just all what comes to mind.


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RE: Failure and frustration - ideas/solutions please

I agree with Ronnie about the time span. I think I would have poured it all the same day and added the vase at the same time. I am sure it is not thick enough to need reinforcement. The crumbly texture makes me think that It was mixed too thin, but I am not a concrete authority by any means. Great idea, hope it works out for you. pour a little in your mold, set the vase and then finish pouring. unmold after 24 hours and mist with water. Place in plastic bag to cure misting every few days. Probably cured too fast in this TX heat.


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