Did I Grind Enough

[wilsonmj88]

I am starting my first epoxy floor project and I am looking for some feedback on my grind. A little background:
- I just bough this home. It was built in 1985. The floor had some minor paint and grease spots that seem to have gone away with my grind.
- I am using an Amorclad Master Kit from Armorpoxy. I decided to grind instead of acid etch due to the condition of the floor.
- This was my first time grinding. I have not yet ground the edges.
- I spent about 6 hours of actual grinding.

I don't really have a point of reference on what is a quality grind. I was wondering if I did enough grinding on my concrete to accept my epoxy system. Please see the pictures below (all dust removed).







I am most concerned about the darker spots and those locations that are not completely uniform. Unfortunately in order to do another day of grinding, I would have to rent all the equipment again so I am avoiding it if possible. I could do some touch up with my angle grinder however.

 

[Shea]

Concrete is rarely uniform. It's hard to tell by pics, but it looks pretty good. Place a few drops of water in various areas to test. If the concrete immediately turns darker and absorbs the water in less than a minute, you are good to go.

 

[Stelzer]

Did you do a thorough cleaning/degreasing before you ground? If not, you'll likely spread any contaminates throughout the entire surface of the floor. You mentioned the grease spots seemed to "go away" with your grinding, but if the grease wasn't removed first, I would make certain and do a thorough cleaning of the floor before any application. In regards to your question as to whether or not you ground enough, I'd suggest grinding more. The circular swirls are indicative of moving faster than your grinders' capabilities.

 

[wilsonmj88]

Thanks for the feedback!

All of the discoloration on the concrete was fairly old. I was having a hard time figuring out if it was general discoloration or actual grease spots. Regardless, I did clean and degrease of any spots before hand with ZEP concrete cleaner and degreaser. The spots remained after following the instructions on the bottle. These spots went away after grinding. Water was absorbed quickly after the grind in these areas. I will do a thorough cleaning of the floor just in case.

I used a Diamabrush with a floor polisher I rented from Home Depot. I just could not get rid of the swirl marks even if I spent 15 minutes working in a single area (arms reach) while moving the buffer slowly side to side. The pictures were also a result of two separate grinds, using this technique, over the entire garage. Is there any advice on techniques or maybe better equipment that will help with this?

Thanks again!

 

[Sumboodie]

This what you rented?

EDCO Concrete Grinder 10" Rental 50200-HD - The Home Depot

Rent a Concrete Grinder 10

www.homedepot.com

 

[Shea]

I used a Diamabrush with a floor polisher I rented from Home Depot. I just could not get rid of the swirl marks even if I spent 15 minutes working in a single area (arms reach) while moving the buffer slowly side to side. The pictures were also a result of two separate grinds, using this technique, over the entire garage. Is there any advice on techniques or maybe better equipment that will help with this?

Thanks again!

The ArmorPoxy kit uses 100% solids epoxy. If you apply it at the recommended coverage rates, you will not have any issues with swirl marks.

 

[Kaizen]

Weigh the cost of the application and your frustration if it does fail due to not enough adhesion. Another day and rental is what i would do until you have all the same light color. If you didnt use a vacuum make sure you do. Might want to use a different kind of machine as sitting on a spot should take up everything or you should notice after a few passes it is getting better. I spent 12 hours on my new 30x36 as an example. 4 years later and zero lifting problems.

 

[Smittybert]

I’m going through this same thing on our new shop. Link in signature. I rented a dual head grinder from United Rentals as I had a lot to cover. If you rent from home depot you could get it before they close and bring it back the next day in the morning (4 hrs or less time from opening) and they will only charge you 4 hrs. (So you can have it all night etc to use for 4 hrs.

 

[Armorpoxy]

We would though recommend strongly that you use the matching primer first since grinded floors become very porous and can have uneven sheens due to uneven absorption. By using the primer is makes the epoxy sit up higher and therefore thicker and helps to greatly reduce or eliminate swirl marks from grinding. Your prep though does seem more than adequate.