Newbie wanting to do Counter and Island in Kitchen

Guys

I'm new to concrete and could use some advice and help from you guys that have been around the block.  I know there is a ton of info on the site and I've been looking and digging as much as possible, so thanks to all of those who have contributed to videos online etc.  That being said I do have some specific questions. 

What I know:

After doing some research I believe the look I like the most is the hand pressed GFRC counters tops.  I likely would do a darker brownish color and come back with a lighter colored slurry.  Below are a few questions I have that I would love some help answering. 

1. I see that Buddy Rhodes makes products for doing this and I also found the Mix Calculator Excel sheet.  If I went with a Buddy Rhodes mix would I still need to order and buy the sand, cement, fibers etc. or is that all included in BR mix?

2. If I do the hand pressed method am I correct in thinking that I'll make my face coat (should be stiff and dry clay like) and then I'll use that same mix and add fibers to it for the back coat? If I do use same mix do I add a plasticizer to it to make it a little more pliable?

3. I plan on a using Melamine for my forms at 1.5" deep counter and forming around a space for an under mount sink.  I'm unclear what guys are using to form sink cut out?  Is it foam?  Are you hot gluing it to melamine sheet?  How do you get round corners for sink cut out?

4. If I do the hand pressed method how long do I need to wait for cure before flipping counter and adding contrasting colored slurry to top?( <-- I'll be doing it when temps are in the 60's in my garage).    Once Slurry is added how long do I wait before working the top as in sanding?  If I do hand pressed with slurry method can I get by sanding counter by hand or do I need to use wet electric sander as I've seen a lot of videos with guys using these.

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Hi Ricky,

Welcome to the forum...

 

1)For hand pressed look I prefer a mix with clay in it so If you want to go the GFRC route I would suggest making your own mix:

Portland (Type 1) 18.5 lbs

Alto-Pozz 4.5 lbs

Sand (#30 sieve preferred) 23 lbs

Water   6-6.5 lbs

KongKrete™ Liquid Acrylic Polymer 2.3lbs

BACKER COATS ONLY-AR Glass Fiber (add last after mixed) 2.6 lbs

Optimum 380 superplasticizer 23-42 mL

There is more information about countertop and GFRC mix designs here.

2) With the mix above it should be almost clay like so yes stiffer.  If you want to practice build a mold with a Plexiglas bottom so you can see instantly how the surface is turning out.  For the backer you can add some additional Optimum 380 to aid with flow.

3)Yes, foam works well for sink knock outs.  Simply use some double sided carpet tape (or something similar).   You can use a sander for the rounded corners then a light sanding with 220grit sand paper to smooth it out.  I would suggest then wrapping with edge form tape or a thick packing type tape before casting

4) I would suggest letting it sit in the mold for at least three to four days with the lower temperatures.  Cover with plastic and blankets to help hold the heat in.  Daily lift the plastic and mist with water to keep concrete hydrated.  Then slurry and you would probably need to wait at least 24hrs to sand off the slurry especially if you have large voids to fill.

My biggest suggestion is to make a small table or stepping stone first to get use to the mix and process.   This way if you have a little practice before tackling a large countertop.  Variegated looks are more of a process or artistic talent then it is a product.  

Tom Fischer



Tom Fischer- Fishstone,CCS said:

Hi Ricky,

Welcome to the forum...

 

1)For hand pressed look I prefer a mix with clay in it so If you want to go the GFRC route I would suggest making your own mix:

Portland (Type 1) 18.5 lbs

Alto-Pozz 4.5 lbs

Sand (#30 sieve preferred) 23 lbs

Water   6-6.5 lbs

KongKrete™ Liquid Acrylic Polymer 2.3lbs

BACKER COATS ONLY-AR Glass Fiber (add last after mixed) 2.6 lbs

Optimum 380 superplasticizer 23-42 mL

There is more information about countertop and GFRC mix designs here.

2) With the mix above it should be almost clay like so yes stiffer.  If you want to practice build a mold with a Plexiglas bottom so you can see instantly how the surface is turning out.  For the backer you can add some additional Optimum 380 to aid with flow.

3)Yes, foam works well for sink knock outs.  Simply use some double sided carpet tape (or something similar).   You can use a sander for the rounded corners then a light sanding with 220grit sand paper to smooth it out.  I would suggest then wrapping with edge form tape or a thick packing type tape before casting

4) I would suggest letting it sit in the mold for at least three to four days with the lower temperatures.  Cover with plastic and blankets to help hold the heat in.  Daily lift the plastic and mist with water to keep concrete hydrated.  Then slurry and you would probably need to wait at least 24hrs to sand off the slurry especially if you have large voids to fill.

My biggest suggestion is to make a small table or stepping stone first to get use to the mix and process.   This way if you have a little practice before tackling a large countertop.  Variegated looks are more of a process or artistic talent then it is a product.  

Tom Fischer

Thank you Tom!  When looking at your "Clay Mix"  I''m curious as to how much that will make?  Using the above mentioned recipe what do I multiply to get the right amount for my project?  I will definitely do a small practice run before taking on the bigger projects.   

1. It sounds like the clay mix will not have fibers in it, but the backer will be a GFRC mix...Did i read that correctly?  

2. How thick should the face coat be? I'm planning on building 1.5" thick counter tops.  I'm guessing that I'll need to compact in the backer as I add it in.  

3. Lastly, Do I need a electric wet sander or can the slurry be sanded down easily enough by hand?

Thanks!

With the pressed look I like to keep my mix around 50 degrees to slow down set time.   I made a piece in the hot summer and it was setting up and didn't get a consistent look.  Another thing to look out for is made sure you don't make same size balls and press them into mold.  I have had this happen and does not look good.  I would really suggest making a few test pieces before trying the kitchen.

Look at this like playing guitar.  99% of people don't pick up a guitar and play perfect for a while. 

1. It sounds like the clay mix will not have fibers in it, but the backer will be a GFRC mix...Did i read that correctly?  

2. How thick should the face coat be? I'm planning on building 1.5" thick counter tops.  I'm guessing that I'll need to compact in the backer as I add it in.  

3. Lastly, Do I need a electric wet sander or can the slurry be sanded down easily enough by hand?

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