How much more do I need to grind for epoxy?

[Casey02L]

Diamond grinding my floor for epoxy and it's kicking my ****..... Anyway how much more should I grind the left side of the picture? Do I need to get it where everything is scuffed (about where its at) or do I need to keep going till it's all "white" like it is down the saw joint I fill with gel crack filler.

Second question is how much life is left in this diamond grinder head?

 

[chops101]

A couple of comments...You know you can use water right? Or is your machine not water resistant?

I just did my floor - 550sf. But half of my shop was broom finish, the other half trowel. Long story how it ended up this way but wasn't my doing. I smoothed everything out. For your floor, I would scuff and smooth everything out, and also acid etch the floor - not really needed but if it comes with your kit it can't hurt.

Looks like your grinding plates are almost worn to nothing....

 

[Shea]

It's always hard to tell from a picture, but from what I can see it looks good. Grinding is rarely going to give you consistant color throughout since the density of the concrete at the surface varies. Just do a simple water drop test in a few areas to verify that the concrete turns dark immediately and absorbs the water.

Do not acid etch after grinding. It's not necessary since grinding is the preferred method. All it will do is introduce water into the concrete which creates another host of issues to worry about. It requires properly neutralizing the acid, a thorough rinsing, and then allowing enough time for the concrete to dry.

 

[Casey02L]

I'm inside an area I can't wash out and it had zero oil so I'm grinding.

I've noticed I can almost tell where each concrete truck poured out. The very first had this dark blue like finish and I almost can't grind it. Then around it is some that grinds easily. While other areas it's a mix. It was a 3k sqft pour and I think the concrete was not the same mix.

I have a primer from legacy industrial so after grinding and priming I think I'll be good.

 

[nyepoxyguy]

Looks good to me. Just make sure that slab is as clean as an operating table before you install any coatings.

 

[Armorpoxy]

Looks to us that it seems grinder enough. Minor color variation as are common.

 

[SunsetsAndFriends]

...

 

[cash68]

Do not acid etch after grinding. It's not necessary since grinding is the preferred method. All it will do is introduce water into the concrete which creates another host of issues to worry about. It requires properly neutralizing the acid, a thorough rinsing, and then allowing enough time for the concrete to dry.

^ this

 

[Armorpoxy]

The grinding head photo had plenty of life left on it. The 'bars' have the diamond chips embedded in them. When the bars are completely worn away, then the plate head is finished. The plate holds the bars.

As the plate spins the diamond chips in the bars grind the concrete, the metal in the bars slowly wears, exposing more diamonds. For this reason on hard concrete you use a 'soft metal bond' type of tooling so the metal wears away faster keeping the diamonds exposed to the hard concrete which makes them last longer, while on soft concrete you use 'hard metal bond tooling' for the opposite reason. Medium bond tooling is available for average concrete.

For most general grinding a medium bond is fine. In city areas for new construction they are using much higher PSI concrete we find so often we need to use soft bond when grinding to get acceptable results and production.

Our Prep Crete Surface Prep Company www.prep-crete.com has a lot of experience with this, so feel free to ask any grinding questions any time.