Hi all. Another newbie here, long time reader and first time poster. I would like to thank Dave for this forum and also everyone who contributes their knowledge and insight.

Well, after doing a few successful wet cast countertops for friends/family using Surecrete X-treme, I decided to try my hand at my own mix design and GFRC. It was unsuccessful and I was hoping some of you can offer suggestions of what I did wrong.

Here was my face coat mix: 8 lb white portland
2 lb vcas 160
10 lb glass sand
2.8 lb water
1 lb polyplex
2.4 oz. Fritz pak supercizer 7

Vert/Backer Coat: 32.2 lb grey portland
7.8 lb vcas 160
40 lb play sand
10.44 lb water
4 lb polyplex
4 oz Fritz pak supercizer 7
2 lb fibers

I poured on Tile board, used melamine for side forms, and used a Gore plastic sink mold. I let the piece dry 48 hrs (60 degree weather with Texas humidity) before demold.

I was low on white portland is the reason I switched to grey on the vert/backer coat.

I know one mistake I made was forgetting to use any kind of release on the sink mold. However, the face coat stuck to the tile board and melamine in many places as well. I hadn't experienced that previously. Also, the face coat seemed a bit crumbly. Like it should be harder and thicker. Some questions are:

Should I have used vasoline or other release on everything?
How thick should a face coat be?
Is there a shelf life for portland (even if sifted),Polyplex or Vcas 160?

Pleased see photos and thanks for any answers, suggestions, or comments.

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I don't know about this 2.4 oz. Fritz pak supercizer 7 but the rest of the mix should have worked. What is tile board? Did it absorb any of the water out of the concrete?

I have experienced crumbly tops when the form sucks out the water.

Thanks for the compliments and welcome. - Dave
I had a similar problem on my first spray up and tend to agree with Jeremy. If you go thin it dries that much quicker. I also was trying to drop the binder as low as possible to reduce the porosity of these cement rich designs.

I have contemplated the acrylic on the back of the face for large molds to extend the working time. I would like to spray it to the back of the face rather than brushing by hand. For those doing this kind of thing what is the weapon of choice? HVLP spray gun?
At what point do you paint/spray it on? Do you do the whole piece at once, or work just ahead of yourself? I have not tried this but working alone on a piece 15-20 sq.ft., it is tough to stay in front of the set. This sounds like it may be the a big help.
You need to spray the whole piece at once. I don't mean the entire kitchen, just each form that is one piece. If your working alone have your backcoat pre-measured and ready to mix so that you can get it in the form while the face coat is still liquid enough to bond.

Steven Hill said:
At what point do you paint/spray it on? Do you do the whole piece at once, or work just ahead of yourself? I have not tried this but working alone on a piece 15-20 sq.ft., it is tough to stay in front of the set. This sounds like it may be the a big help.
Thank you for the replies. This gives me plenty to work with. I'll give it another shot this weekend.

Hello Brandon,


I'm going to attempt this technique of brushing on the diluted Forton to keep the face coat workable.  I've been having some similar problems with the high temps and low humidity here, of which I'm sure your use to.  I'm using your old mix design and may have to step up on the plasticizer or maybe a little extra water to help eliminate the face coat setting up so fast.  I'm up to at least 3 oz. of advacast and may end up going as high as 3.5 to 4 with the next mix.  Is a slight amount of extra water necessary or will it hamper the mix? Thanks


Gore Design Co. said:

I dilute the Forton 50/50 with water and paint it on with a disposable paint brush.

Robert Winckler said:
I had a similar problem on my first spray up and tend to agree with Jeremy. If you go thin it dries that much quicker. I also was trying to drop the binder as low as possible to reduce the porosity of these cement rich designs.

I have contemplated the acrylic on the back of the face for large molds to extend the working time. I would like to spray it to the back of the face rather than brushing by hand. For those doing this kind of thing what is the weapon of choice? HVLP spray gun?

Slurry that baby up and put a little acid stain on it and sell it on Craigslist. Get at least your materials out of it. I experienced a melamine failure this past week. The face of the melamine blistered and the facecoat stuck to it. Check your mold and make sure that this did not happen to you.

 

also might want to check the quality of the melamine board. One type uses this cheap sprayed on crap and thats the kind that blissters. You can usually tell when you look at the edges of the board if it is the cheap stuff.

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