Diamabrush vs. Grinder... Plus some other epoxy prep questions.

[toreadorxlt]

Long time lurker/reader, first time post. I figured I post something to help somebody else, after shelling out the money for two prep tools.




I did a ton of searching on here before grinding my floor in prep for epoxy. I landed on the diamabrush concrete floor prep tool on a Floor sander. I rented it... and here are my findings:

1. way slower than I thought. I have 1100 Sq ft.. It was painfully slow.
2. I tried cutting on water, much faster, but still slow. Slurry mess was real, but could have been controlled with constant attention and copious amounts of water.
3. Maybe the removal tool would be better... less TPI would maybe be harsher on my concrete?

After realizing it would take me 3 days to prep my slab, I decided to rent a small edco grinder. The local renter only had 30G Diamond Dots for it. I didn't know what to expect, so I rented it for the minimum amount of time and figured i'd be out $120 if it didnt work. Here's what I came to:

1. Still slower than expected, but 2X faster than the diamabrush.
2. Surface finish with 30G diamond dots was good to me. Not too rough, but it absorbs water now.
3. I ground without the vacuum hooked up, while wearing a N95 mask. with the dust shroud adjusted right, this was acceptable to me. Perhaps based on my next question, I should have ran the vacuum the whole time.
4. Total grind time with edco was 11-12 hours. About 100 sq ft/Hr. I found the back of my slab to be way harder than the front.


I am having some problems getting the dust CLEAN CLEAN before coating. I vacuumed the initial mess, but theres still some dust in the ground concrete the vaccum wouldn't touch. A stiff broom seems to get the dust loosh-ish but I feel like i can always sweep more up no matter how many times I vaccum/sweep. Any suggestions on how to take care of the dust after grinding?

 

[LegacyIndustrial]

In most cases a triple broom/vac and blow will get it pretty well ready.
If it's excessive then mop or pressure-wash it but let it dry 4-5 days before coating if pressure-wash.

Good luck.

 

[SolarColumbia]

I just used a regular garden hose and nozzle to keep wetting it down and brushing it out the door. I did this probably five times and when dry I was getting virtually no dust on my fingers when swiping it. I let it dry for a week.

 

[toreadorxlt]

In most cases a triple broom/vac and blow will get it pretty well ready.
If it's excessive then mop or pressure-wash it but let it dry 4-5 days before coating if pressure-wash.

Good luck.

Thank you very much! I'll try a few more sweepings.

I just used a regular garden hose and nozzle to keep wetting it down and brushing it out the door. I did this probably five times and when dry I was getting virtually no dust on my fingers when swiping it. I let it dry for a week.

If it comes down to this i'll follow suit! Drying is really tough in this humidity/heat. I also don't have a garage door (backorder). Im having some issues with condensation at the moment due to 100 degree air hitting 65 degree frost walls. I dont know if now is even a good time to coat with the weather and no garage door. I might hold off a month until my door comes in and I can regulate the internal environment a little more?

 

[Hawkins]

So on 1100 sq ft, did you give thought on renting the double disc edco? or was it available. I have about the same (4 car garage) and this is the part I dread the most. I can rent the edco you had or an edco with 2 discs (6 "grinders") for like 160ish.

 

[LegacyIndustrial]

Hawkins, many places are renting planetary machines these days, see if you can get one, much better than the double-disc.
Shot-blasters are rented more frequently as well.
Good luck

 

[Armorpoxy]

Agree a planetary grinder which seem to be coming more available at rental houses is a great way to go and better and more forgiving than a dual disc.

We wouldn't recommend shot blasting a garage floor since in the hands of a novice user it can create significant 'lawnmower lines' from overlapping the passes, plus the shot blasters being a bit unwieldy don't get close to the edges. Shot blaster lines won't be hidden with a standard garage coating either.

 

[Magnify]

I stopped by my local Home Depot to see what they had - the had the diamabrush for rent, and although it has vacuum pickup, the guy said none of their vacs work well with it and just do it wet.

I have plenty of time to let things dry, but really didn't want to introduce all that water - but then I don't have to worry about collecting all the dust.

 

[LegacyIndustrial]

NEVER GO WET!! It's ok to sprinkle a little water in front of the head but a wet grind is a MESS! Slurry is a real PIA.
Good luck.

 

[Imatk]

I was told the same thing by the Home Depot guy... do it wet.

I have a feeling they say that to limit the amount of times they have to replace the stones.

I did mine dry and hooked up my shop vac to it... worked like a charm.

I also couldn't get the dust out with a normal garden hose. Had to pressure wash twice to get everything to the point where I could rub my finger on the concrete and not get any residue.

 

[FJ4FUN]

Diamabrush is virtually useless for everything other than prepping for a recoat of an existing epoxy floor.

Twin head Edco is always better than the single head unit. (unless you're hauling it into a basement!)

As far as grinders go, the planetary grinders are far superior. Get as much grinder as you can afford...

An appropriately sized HEPA vacuum is mandatory and make sure that the grinder you rent has a functioning shroud in place! Also, make sure that the rental company includes a floor wand for the HEPA so that you can easily use it for the final clean-out.

MAKE SURE you have sufficient and correct power available for the machine you rent. Nothing is more frustrating than renting/hauling all that EQ and then find out that it throws the circuit every time you hit the GO switch. If there is any doubt find/rent propane powered grinders.

Light water misting in front to the grinder path will help to keep the diamonds cool and cutting. Too much water will create a wet slurry that is a PIA to get up if it dries!!

Shot blasting is NOT for your typical DIY project IM-notso-HO.

Typically, a good HEPA vacuum followed by a blowout with an electric leaf blower will get rid of any remaining dust. If needed a good flush with city pressure water will take care of the rest. Wolverine Coatings BondTite 1101 primer does not require "bone dry" concrete to be applied.

While you are at it, we always recommend that you make sure to blow out the garage top to bottom to make sure no dust/debris shakes free and into your fresh epoxy or final clear coat.

 

[toreadorxlt]

So on 1100 sq ft, did you give thought on renting the double disc edco? or was it available. I have about the same (4 car garage) and this is the part I dread the most. I can rent the edco you had or an edco with 2 discs (6 "grinders") for like 160ish.

I was limited by local options. Im sure I should have gone closer to the city and got a dual head... but thats hindsight knowing what I know now. The blisters on the inside of my thumbs have healed and I forgot about the 12 hours I was strapped to it haha.

 

[Hawkins]

Sorry to take so long to read the responses -- I don't believe I have a planetary grinder available for rent in my area. We have a decent amount of rental houses around but none are offered.

The only options I have are a single disc grinder, a dual disc grinder, and a floor buffer with grinder attachment. Shot blasting is available but much more $$ to do.

 

[toreadorxlt]

Sorry to take so long to read the responses -- I don't believe I have a planetary grinder available for rent in my area. We have a decent amount of rental houses around but none are offered.

The only options I have are a single disc grinder, a dual disc grinder, and a floor buffer with grinder attachment. Shot blasting is available but much more $$ to do.

Rent the biggest one you can find! I wish I had a 2 head one when I did this.

 

[Hawkins]

Got it. Will do--- I would have installed my floor eons ago but I dread the prep work! I can't find a local company to do it for me either.

 

[Armorpoxy]

Hi, if you look around for companies that do epoxy coatings or terrazzo, they have the diamond floor grinders and could give you a price on prep. It probably won't be inexpensive since they have to roll up an expensive truck with a couple of guys that has expensive grinders and vacuums on it and it's a 'lost day' so they need to be reasonably compensated.

 

[CapriMikeC]

My first post here...

Based on recommendation from Legacy Industrial, I also rented the EDCO grinder from Home Depot. It was very slow, even when I added weight on top as suggested. In my experience, the EDCO worked fast and hard where the floor was uneven. Where the floor was smooth and even, the EDCO just seemed to float and wouldn't bite.

I used my wet/dry vacuum paired with a Dust Deputy. The cyclone worked very well at separating the dust before it got to the vacuum. However, the little wheels for the bucket and the method of tying it to the vacuum were rickety and frustrating.

I pressure washed twice after grinding.

 

[Imatk]

I had minimal low spots on my floor, I think mostly because it's a somewhat new house (10 years is new I guess?) For those I just spot ground with an angle grinder.

For the most part though the single-head grinder worked perfectly. I don't think my concrete was terribly hard either though.

But it took two power washes to really clean everything out. I started using just a garden hose and broom... way more work and way more frustrating.

The power washer does all the work and a lot less frustrating.