Sanding Concrete

Traditions2

I have a big acid stain job to do in a warehouse. They are only doing the front office area and a "kitchen/meeting room." The concrete is very old. The building used to just be a famr implement shed. There are some oil markings on the floor. I am not as worried about getting those completely up. Sometimes those add to the finish. THe owner understands that. However, I was talking to another guy and he said instead of powerwashing and cleaning floors he sands them first. Said it works much better and keeps from getting mildew and mold??? Never heard of that. However, sanding would work well to take any paint or contaminants on the top of the substrate off. Ok, finally my question. Will sanding leave a rough finish? I did another commercial building with paint and the owner had sanded the floors first. But it felt like 100 grit sandpaper. Can floors just be sanded with lighter grit. Would this be ideal for an acid stain project or just wash it? Ok, I am babbling and don't even know if I asked a question!!!

WisePainter

#12 sanding disk on a rented circular floor sander.
They look like a commercial floor buffer but with a bit more of a kick.
If this is the first time you are using it I recommend you start in a large area, without anyone watching.

Lightly lift to go left, gently lower to go right.

And I do mean LIGHTLY and GENTLY, or that puppy will violently jerk away from you.
Trust me, I put a hole into the bottom of a wall the first time I ran the beast.

The guy who watched me do it told me it was "like dancing with a lady, a big mean ugly lady who likes to lead"...

Have fun.


EDIT: The #12 disk is the equivalent of using medium grit on tape joints.

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My advice: Hire a real painter to do it.

JBBS

if the concrete is "very old" there is a chance the stain won't take at all. Be careful.

Traditions2

even after sanding? Whats best way to see if it will take the stain? pour on water and see if soaks in???

WisePainter

*crickets chirping*

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My advice: Hire a real painter to do it.

Traditions2

chirp chirp

WisePainter

Tough call man can you post a couple of detailed pics? With a stain it is going to be a different ball game than an epoxy or any other coating, you have a larger sweet spot with the stain since the chance of peeling is far less.

chirp.

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My advice: Hire a real painter to do it.

Traditions2

I went to a rental place and not sure they really knew what I wanted. They had a machine that has 4 things with what look like some sort of square bits. they were afraid it would leave lots of circular marks. I tried explaining what I was wanting. Wise, the sander you are talking about just takes a circular disc sanding pad? They didn't have that. They had a buffer and different brush attachments and one that was like sos type material. I want to make sure I have the right machine before I get started on this. Maybe i could just rent the floor scrubber and get it clean that way??? If anyone knows the exact name of the machine I want I'll call the rental place back. Thanks.

WisePainter

The one I used was not as fancy as this one, but it is the same concept. Like I said, be careful these monsters are strong and without a light touch it will escape from your grip quickly.
The sanding disk I prefer is the #12, it looks like rubik's cubes glued to red paper but surprisingly it does not dig into the floor. You will remove the center nut and washer, sandwich the pad between the 2, tighten the life out of it and begin.
The learning curve is about 3~4 pads so purchase way more than you will need. You may find them ripping off the minute you begin so get ready when you pull the trigger to get it moving!
There will be some dust but nothing like a wood floor being sanded, or drywall sanding. Wear a simple dust mask.

Go to the place the local flooring guys use for materials (no not HD lol), it will be easier to get what you need there.

__________________
My advice: Hire a real painter to do it.

WisePainter

You could always drop acid.


On the floor to etch it.

__________________
My advice: Hire a real painter to do it.

Aggie67

Never used it, but we redid a floor in a food plant 3 years ago. We were responsible for pouring new slabs, and there was another guy that was stripping off the paint from the floor in the warehouse in prep for an epoxy coating (they were turning it into production space). Huge square footage. He used this thing:

http://edcoinc.com/floor-grinders-2ec.html

He did the grinding work over night in one shift. I know Sunbelt rents them.