10 grit stone

[randyrhoadsriff]

My Sherwinn Williams rep came out to look at my garage floor yesterday.He said acid etching would not be suggested due to the slick finish.This is a 1 year old floor with no stains,oil or imperfections.I am going to rent a floor grinder from a local rental place but they due not have a diamond grinder.It was suggested to use a heavy floor grinder with a 10 grit stone.Do you guys think this will work? I have one reserved for tomorrow but want to make sure it will be aggressive enough.Any suggestions would be greatly appreciated.

 

[Timm129]

I just used a concrete slab grinder today for the second half of my 4 car garage. It had a sealer on it and was only about 4 years old. The grinder took off the sealer but I did have to rotate the stones every so often as they became filled with the sealer material and it took longer than the front half of my garage that didn't have the sealer

 

[randyrhoadsriff]

Thanks Timm,
A few people here say don't use the stones and some say it works well.Since my floor is new and hasn't aged I think it might work.If all else fails I break out the acid.

 

[nils]

I'm about to go pick up my rental grinder as well. Any advice on a good grit stone? Coincidentally, Sunbelt told me they had 10 grit stones as well, and I'm not sure what to get. They seemed to think their diamond wheel was a bit worn.

 

[krooser]

I sanded my floor to smooth out the texture and get rid of the fiber from the fiber mesh concrete is used.... I'm not sure why so many guys are concerened that their floors are too smooth.

Two years ago the general concensus was to grind the floor only to remove imperfections. I sure wouldn't grind my floor.

 

[randyrhoadsriff]

Ok kimosabees,
I got the Edco floor grinder with the 80 grit and the 10 grit stones and it is a waste of time and money.It would smooth out slight imperfections and remove paint but thats about it.I tried adding weight to the front of the machine(which helped slightly),wetting the floor and even lifting the rear up so the stones worked harder.I am going to take a diamond cup grinder and rough it up for the rest of the day and then acid wash it.I could get diamond bits for that machine but they were on the other side of town and cost $100.00 a piece,for a total of $300.00.Maybe I'm hard headed but I'll find out soon.

 

[nils]

Incidentally, I rented a handheld 7" diamond grinder from HD today that worked out pretty well. I bought a 7" diamond wheel from Harbor Freight (see: http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=66353)

I also rented the Blastrac vacuum that works with the grinder. That thing did a fine job. I didn't have to clear a single clogged filter or anything. I'm pretty happy I didn't have to clean out my shop vac afterward, either. I would highly recommend anyone grinding their floor to get a vacuum. the dust is overwhelming otherwise.

The only disruptions were my 20A breaker tripping when I would load the grinder too much.

I also learned the technique for using the grinder to avoid big gauges. I found that being somewhat gentle with it, without applying much (if any) downard pressure) resulted in the most even cutting.

The floor is amazingly clean now. All the grease/spilled paint, etc. is gone. The only problem I've got now is that the surface is too smooth. Much smoother than 80 or 100 grit. I was hoping to put the primer on tonight (I've gone with the Wolverine stuff from Fred), but I guess I should acid etch it to get the roughness where it needs to be? Any advice?

 

[nate379]

Check the thread I started about the floor being too smooth.

Seems that putting the acid full strength roughs it up ok.

 

[thegarageguy]

If the slab is "smooth" or hard trowelled, the grinding will need to be a bit more aggressive. Stones are useless regardless. Acid is not only enviromentally hazardous but very inconsistant. The use of diamond inserts and weight are needed to remove the cream of the surface, in which case its hard trowelled. Then the poures of the concrete are exposed and ready to accept coatings.

If you grinded it with diamonds then you should have a giood surface to work on. No need for acid then. If you feel you need to, then make sure you neutralize it before you proceed.

Good luck

 

[randyrhoadsriff]

I also got a diamond cup from Harbour Freight.They didn't have any 7" so I had to go with a 4 1/2".It is doing a good job ,but it takes a year and a day with such a small wheel.Pretty much knocked the bark off this slick muther and pressure washed it clean.I found if you keep the grinder moving with light pressure and change directions often that you don't tend to dig in too much.The surface is allowing much more moisture to soak in so it is getting closer to what I need.I figure maybe start with a 25 % muriatic acid wash and I should be there.And yes I am hard headed !

 

[nils]

I just finished the acid etch. I divided the garage (~400 ft^2) into 4 quarters. It was sort of interesting to watch the stuff work, but from afar as the vapor is awful. I used the muriatic acid undiluted. I found it difficult to spread evenly using my watering can. You could clearly tell the areas that were etched and those that were not. In the end, I decided to etch (for a second time) the critical areas where the tires will contact the floor, rather than go over the entire floor, due to laziness.

I neutralized the acid with baking soda.

I used 3 gallons of acid and a little less than 32 lb of baking soda (4lb x 8) (probably more baking soda than necessary, but I wanted to be on the safe side). And lots and lots of water.

Bottom line is the acid roughed things up well, as nate said. I got a good rough surface. Can't wait for it to dry and so I can put on the epoxy!

 

[nate379]

Yeah use it 100% no dilution.

I am using a garden sprayer to spray it on the floor which seems to work well. Spray the floor and then with a deck brush scrub it down. Give it 15-20 mins and then scrub again only the other direction. Let it sit for another 15-20 mins and then rinse it off.

It will turn yellow and lots of fume. I suggest wearing a paint mask.

I used amonia to rinse and then TSP for a final wash.

I did lots of reading on google and there seems to be a million and one ways to skin the cat really. If you go by the directions of the Quick Crete it's just using their "bondlock" stuff that didn't etch the slab at all.