I am making some practice forms and experimenting with pigment before
making my own concrete countertops. I have the book by Du-Teng Cheng
and he says to sand using water, diamond sand paper and an electrical
sander. I am not finding these at any of the home improvement stores.
Can you use regular sandpaper? Anyone have any experience with this?

In article , MC
wrote:

I am making some practice forms and experimenting with pigment before
making my own concrete countertops. I have the book by Du-Teng Cheng
and he says to sand using water, diamond sand paper and an electrical
sander. I am not finding these at any of the home improvement stores.
Can you use regular sandpaper? Anyone have any experience with this?

You'll find it at lapidary suppliers -- people who cut gems and other
stones. It's about $1.00 per square inch. Dr. Cheng probably makes
enough profit from his countertops to afford lots of it.

http://www.xmission.com/~ranthon/coated-abrasive.htm

-chib

--
(email: change out to in)

I should clarify that by "these" I mean the diamond sanding pads is
what I can't find easily. I understand they are also very expensive.

(MC) wrote in message . com...
I am making some practice forms and experimenting with pigment before
making my own concrete countertops. I have the book by Du-Teng Cheng
and he says to sand using water, diamond sand paper and an electrical
sander. I am not finding these at any of the home improvement stores.
Can you use regular sandpaper? Anyone have any experience with this?

MC writes:

Can you use regular sandpaper?

Yes, but you won't get much mileage out of it. The portland cement itself
is very soft but any quartz or granite aggregates will be very hard.

Consider a rubberized diamond polishing pad in a rotary polisher:

http://diamondtoolstore.com/

"MC" wrote in message
om...
I am making some practice forms and experimenting with pigment before
making my own concrete countertops. I have the book by Du-Teng Cheng
and he says to sand using water, diamond sand paper and an electrical
sander. I am not finding these at any of the home improvement stores.
Can you use regular sandpaper? Anyone have any experience with this?

I used regular belted sand paper to remove some glass from some doors I was
making. Yep screw up by that much. I should have used the ones for glass but
they were way expensive.
You might try harbor freight for what your looking for. The stuff is for
sure not contractor quality but for me it works just fine.

I'm in the midst of pouring my countertops and heres what I'm using
and what advice I can give.

I bought this polisher from Harbor Frieght:

http://www.harborfreight.com/cpi/cta...emnumber=46507

It works fine.

As far as sanding media goes get the diamond pads anything else will
not hold up. I have access to an autobody shop and tried the best
wet/dry paper I could get and it didn't hold up for more than 5
minutes of hand sanding. I ordered from Cheng Design:
https://www.concreteexchange.com/shop_catalog.jsp

I ordered a 200, 400, 800, and 1500 grit pads and the Velcro backer
piece.

As far as sanding the 200 takes the top down fast and easy, but its
much to aggressive for the sides of my 2 inch thick counters. It
brought up the aggregate very very quickly. Since then I've only used
the 800 and higher pads on the sides. (I don't want much aggregate to
show, on the top the 200 brings up specks, on the side it brings up
pebbles! )

Grinding is messy and wet! GET A WATERPROOF APRON! Concrete can and
will give you a chemical burn if your skin is exposed to it for a
prolonged time! This is not a suggestion, It happened to me doing this
job. Get an Apron!!!

For the concrete we started using one 60 lb bag of Quikrete fiber
reinforced and one 80 lb back of Quikrete 5000 mixed, which gives you
a hair over one cubic foot of concrete. We've since located a local
supply of concrete fibers and are now using just the quikrete 5000
with these fibers added.

For vibration we've been using two sanders on either side of the mold
and leaning in to each other while working back and forth round the
mold. We've also covered the sander with a plastic bag and gently
plunged it into the concrete. We've also given the mold a good beating
with a rubber mallet. I've also heard that you can use a saws-all to
vibrate, but I've not tried this one, but see no reason why it would
not work.

The only other major advice I'd give is to allow the counters to stay
in the mold for a minimum of 7 days and 10 would be better. RESIST THE
URGE TO LOOK!!!! Its tough I know! But the corners and edges need the
time to really firm up and set so that when you do remove the counter
they don't crumble.


"SQLit" wrote in message news:rC4Vc.71948$Lj.26123@fed1read03...
"MC" wrote in message
om...
I am making some practice forms and experimenting with pigment before
making my own concrete countertops. I have the book by Du-Teng Cheng
and he says to sand using water, diamond sand paper and an electrical
sander. I am not finding these at any of the home improvement stores.
Can you use regular sandpaper? Anyone have any experience with this?

I used regular belted sand paper to remove some glass from some doors I was
making. Yep screw up by that much. I should have used the ones for glass but
they were way expensive.
You might try harbor freight for what your looking for. The stuff is for
sure not contractor quality but for me it works just fine.

How much use can you expect to get out of these diamond grinding pads?
Are we talking 1 countertop or dozens?

(Mike Glenn) wrote in message . com...
I'm in the midst of pouring my countertops and heres what I'm using
and what advice I can give.

I bought this polisher from Harbor Frieght:

http://www.harborfreight.com/cpi/cta...emnumber=46507

It works fine.

As far as sanding media goes get the diamond pads anything else will
not hold up. I have access to an autobody shop and tried the best
wet/dry paper I could get and it didn't hold up for more than 5
minutes of hand sanding. I ordered from Cheng Design:
https://www.concreteexchange.com/shop_catalog.jsp

I ordered a 200, 400, 800, and 1500 grit pads and the Velcro backer
piece.

As far as sanding the 200 takes the top down fast and easy, but its
much to aggressive for the sides of my 2 inch thick counters. It
brought up the aggregate very very quickly. Since then I've only used
the 800 and higher pads on the sides. (I don't want much aggregate to
show, on the top the 200 brings up specks, on the side it brings up
pebbles! )

Grinding is messy and wet! GET A WATERPROOF APRON! Concrete can and
will give you a chemical burn if your skin is exposed to it for a
prolonged time! This is not a suggestion, It happened to me doing this
job. Get an Apron!!!

For the concrete we started using one 60 lb bag of Quikrete fiber
reinforced and one 80 lb back of Quikrete 5000 mixed, which gives you
a hair over one cubic foot of concrete. We've since located a local
supply of concrete fibers and are now using just the quikrete 5000
with these fibers added.

For vibration we've been using two sanders on either side of the mold
and leaning in to each other while working back and forth round the
mold. We've also covered the sander with a plastic bag and gently
plunged it into the concrete. We've also given the mold a good beating
with a rubber mallet. I've also heard that you can use a saws-all to
vibrate, but I've not tried this one, but see no reason why it would
not work.

The only other major advice I'd give is to allow the counters to stay
in the mold for a minimum of 7 days and 10 would be better. RESIST THE
URGE TO LOOK!!!! Its tough I know! But the corners and edges need the
time to really firm up and set so that when you do remove the counter
they don't crumble.


"SQLit" wrote in message news:rC4Vc.71948$Lj.26123@fed1read03...
"MC" wrote in message
om...
I am making some practice forms and experimenting with pigment before
making my own concrete countertops. I have the book by Du-Teng Cheng
and he says to sand using water, diamond sand paper and an electrical
sander. I am not finding these at any of the home improvement stores.
Can you use regular sandpaper? Anyone have any experience with this?

I used regular belted sand paper to remove some glass from some doors I was
making. Yep screw up by that much. I should have used the ones for glass but
they were way expensive.
You might try harbor freight for what your looking for. The stuff is for
sure not contractor quality but for me it works just fine.

Let me put it this way I am pouring 52 square feet of counter and from
what I've seen so far the pads would do this job and have several more
jobs left in them. How many is hard to say cause I'm not done
yet...but if I had to guess I'd say at the pads would last through at
least 300 square feet of counter and maybe more. All this is going to
depend on how much agg you plan on exposing and how long you wait to
grind the concrete as it gets harder everyday.


(MC) wrote in message . com...
How much use can you expect to get out of these diamond grinding pads?
Are we talking 1 countertop or dozens?

In the 2 samples I have made, I kind of like the look unsanded. Any
comments on choosing not to sand?

(Mike Glenn) wrote in message . com...
Let me put it this way I am pouring 52 square feet of counter and from
what I've seen so far the pads would do this job and have several more
jobs left in them. How many is hard to say cause I'm not done
yet...but if I had to guess I'd say at the pads would last through at
least 300 square feet of counter and maybe more. All this is going to
depend on how much agg you plan on exposing and how long you wait to
grind the concrete as it gets harder everyday.


(MC) wrote in message . com...
How much use can you expect to get out of these diamond grinding pads?
Are we talking 1 countertop or dozens?

Not sure what to tell you on this one... but I'll say that if you like
what you see I'd wait between 2 and 3 weeks then start with 400 grit.
You should be able to maintain that unsanded look but still smooth the
concrete to the touch.
Not sure what this will end up lookin like for sure, but its the best
recommendation I can give you based on my limited experience :-)


(MC) wrote in message . com...
In the 2 samples I have made, I kind of like the look unsanded. Any
comments on choosing not to sand?