Disc sander instead of an EDCO grinder?

[V-10 Killer]

I just picked up 2 1/2 kits of Epoxy-Coat and emptied and swept/blew out the garage tonight. Tomorrow I'm going to etch the floor, and if it's dry by the afternoon, start caulking the control joints. Since this is brand new concrete (the most it's had on it yet is sawdust), will I be able to rough it up with a buffer/sander and some 80 grit sandpaper. No place local has a floor grinder, and the one place I found wants $75/day for the grinder and $70/day for the stones! Now, nobody needs to tell me that the grinder is the preferred method. But what I would like to know is, can it be done with the floor sander? Epoxy is nice, but I'd prefer not to have to pay more to put it down than I paid for the concrete itself. Anyone done it that way already? How many sanding disks did you go through per hour? It's been down just shy of two months, and has no fiberglass in it.

Thanks

 

[Down Under Bloke]

No idea but im interested to know how you go with it. I doubt the paper will last long.

 

[SteveL]

If your concrete is new and has no coating or oil/grease spots, why on earth would you spend the time and $$$ grinding the floor??? I guees if you have some high spots that you want to get rid of, OK, but otherwise, acid etching is all you need to do. Save the money and the back aches and get'er done!

 

[noyu]

I did tried the handheld angle grinder with a grinding disc and it works.

Its not the quickest way and it might only take out some small chucks or imperfection like the size of a quarter but it work.

I use one of those grinding disc ( I think it either 6 or 7 inches) with the backing plate (something similar to the people auto body shop use).

If you have or can borrow a grinder you might want to give it a try because those grinding disc is cheap (I think 3 or 4 bucks each) and get the coarsest one you can get I think is 24 grits.

 

[V-10 Killer]

Primarily, I'm just trying to do a quick knock down of any little specs left by the edge of the power trowel.
I'll give the 12x18" sander a try and post up how it goes.

Thanks everyone.

 

[V-10 Killer]

Well, I rented the sanded yesterday. I got the rotary sander instead because I figured it would just sand better. Used 36 grit pads. They would do about 50 sq ft really well, but wore down pretty fast. I could still use each pad for at least 300 sq ft, but you could feel that the sharp edges were gone off the paper pretty fast.
I vacuumed the dust off last night before I quit but haven't really scrubbed the concrete to get the remaining dust out of the porous surface. I'm kinda disappointed with it. Even with the 36 grit paper, the concrete feels pretty smooth. I know the embedded dust has something to do with it. I've already etched it once, and am hesitant to use water in there with the unfinished drywall on the walls now.
If I can get it cleaned up, I'm going to start epoxying tomorrow. Gray parking pads the first day, Blue border the second day. I'm hoping to have it fully cured by the time I come back from deer camp this coming Sunday so I can start setting the furnace and stuff in place.

 

[thegarageguy]

acid etching is very inconsistant. It may penetrate one area and then in others not enough. renting a good grinder with diamond inserts is the proper way to prep. consider it insurance. it may prevent you from wasting your hard earned epoxy money.

also, reread your own signature. wise words that work for more than just cars.

 

[67 455 Bird ragtop]

With fresh unsealed concrete how do you determine if it's course enough to coat?? I have talked to my concrete guy and told him I would be epoxy coating my floor and I didn't want it shiney or sealed. He showed me a surface that looked and felt fairly rough. But how do you determine if it needs to be ground or etched to make it rough enough ??? I hope to have my foundation poured just before or after thanksgiving ...

 

[snorvet]

I would use a rougher sandpaper than 80 grit. I believe I used 36 grit on mine, when I sanded down epoxy bubbles between coats. . Probably went thru 8 discs on a 22'x24' garage. A good sanding and etching should work well for prep on a new concrete floor. Give Epoxy-Coat a call with your questions also. They were helpful when I called them. Also make sure that the floor is rinsed well and is completely dry before applying epoxy.

 

[V-10 Killer]

I did use 36 grit. I'll have to see what the surface feels like after cleaning again, but right now it feels like textbook paper with the dust still in it. And I can still see the power trowel marks from where it started to flash dry. I think that will hide with the epoxy and extra flake I have though. I'm doing one coat only. For what it would cost me in epoxy, I could have done 2 slabs at 4" thick. So I don't have to worry about sanding after the first coat dries.
I vacuumed up the surface dust yesterday and intend to go out tomorrow and scrub and vacuum the floor multiple times until I don't get dust anymore. Am I going to have to rinse it after sanding? If so, I won't be able to epoxy this year. After Wendsday, it's supposed to be highs in the low 40's for at least a week. It'll take forever to dry, and I still have too much to do to be able to move stuff in before it snows.

 

[mhoffm911]

V-10Killer,

If it's any consolation, I am fighting the same battle you are (with the weather - I'm in Ohio). I spent all day today moving stuff from my garage into my storage unit and just got home from buying the Rustoleum Professional Epoxyshield. I went with them because I could go buy it immediately without having to wait for shipping and worse weather moving in. I hope to get mine done on Wednesday after powerwashing and etching tomorrow morning. I'm going to be pushing it with the drying period before putting the epoxy down, but really don't have any other choice based on the weather.

Of course, on a side note, I just HAD to go to an auction on Friday and buy 21 bicycles to resell - so of course they are all lined up in my garage at the moment. I've got them on Craig's list and sold 3 tonight. I'm lining them up outside as I do my garage clean out. The bikes will pay for my garage flooring.

Did I mention that I also bought 42 bags of blow-in insulation this weekend? I have them stacked in the garage right now too. I can put them up in my over the garage attic storage for now. I plan on blowing it in this weekend.

 

[snorvet]

V-10killer,

You probably dont need to rinse again as long as you rinsed well after etching. A good rinsing after etching should have removed the acid etching residue. Hopefully the dust you have now is from sanding and not acid etch residue. You need to get the dust off as much as possible. After you scrub and vacuum, rub a dark cloth on the floor and see if it still picks up dust.