New garage has sealer, grinding didn't remove it

[Mechie3]

Just closed on a new house where the garage floor had sealer applied by the contractor (we didn't build the house ourselves, but it hasn't been lived in). I rented a grinder from sunbelt and used it for several hours going over every spot several times. 70% of the area doesn't bead up, but other sections do. Even going over the same spot for 10 minutes didn't affect it. when I returned the grinder this morning (1 day rental) they said they gave me the roughest stones available.

I've read that some people have luck with hand grinders. Are we talking about the standard angle grinder? How do you prevent the grinder from digging in at an odd angle making an uneven surface?

It's a 3 car garage so any method will take a lot of time, but I prefer not to go to town on my knees with a 2x4 block and sand paper.

Thanks.

 

[AlphaGarage]

An angle grinder will cut in pretty good. Using a larger one, 7" instead on 4.5", will make it less likely that you'll cut deep crescents. Diamond cups will work best. There is a bit of a learning curve to find that right touch.

Here are a couple of project from forum members who used angle grinders to prep the entire floor.

http://www.garagejournal.com/forum/showthread.php?t=20542
http://www.garagejournal.com/forum/showthread.php?t=26308


It's a bot more involved to take this route, but you're pretty much assured that at the end of the road the floor is ready to accept the coatings.

 

[thegarageguy]

Goes to show that just because they rent them doesn't mean they know how to use it. Stones are not meant for prepping concrete. What you needed was diamonds. Even diamonds have different grits. What rental places typically have is 30 grit, which still may not suffice.

You may want to ask for your money back.