Etching, grinding, prep for epoxy issues

[Turbotboz]

I'm trying to prep my garage floor for to lay an epoxy. I'll start with my experiences in the last week. The end goal was to get the floor to a profile ~120 grit sandpaper.

Day 1- Acid etched with supplied materials. Wasnt happy with results, no profile.

Day 2- Acid etched with 4:1 muriatic acid, wasnt strong enough till I got 1:1. This was starting to profile the concrete but it almost seemed to be soaking into the concrete (even after continuous scrubbing/rinsing after applying). I was nervous to have contaniments left on the surface of the concrete from the acid.

Day 3- Decided to bite the bullet and go with the grinding method. A friend and fellow forum member had rented the Diamabrush from HD the same weekend. After he used it, I jumped at the oppurtunity to use it myself. It seemed to be working and it did take a thin layer off of my 3 car garage floor, but it seemed insufficient.

I cleaned a portion of the garage and the floor is very porous but it still has practically NO profile. At this point I have became extremely frustrated with this project, I've never felt more defeated on an DIY effort. It's my impression that everyone grinding with the Diamabrush has had reasonable success.

I talked to my friend who grinded his floor prior to me and he also has not acheived a profile of ~120 grit paper or near that. I thought the blades could of been dull, so I returned to HD. After the lengthy discussion, turns out the blades were still newish condition. At this point the employee is confused at the lack of performance as well and decides to look up the diamabrush parts online. Turns out the HD computer and their training said this was the concrete grinder=

^ Which actually appears to be the Mastic Removal tool....

Further investigating determined this should of been the supplied concrete prep tool =

Of course home depot doesnt have the correct tool and they will have to approve and order it (a process that can take 3 weeks).

So here I am even more frustrated with this floor, debating what to do next. I've called around and found other concrete grinders but it will costs another $200 to go that route.

My questions for anyone familar with concrete grinding-

1. Is the second picture above, known as the concrete prep tool, the unit many have used with success?
2. Will I ever achieve a profile of 120 grit sandpaper via grinding?
3. Do I NEED to have a profile of 120 grit or is the porous surface sufficient?
4. Will the Edco concrete grinder with Diamond blades get me to the desired profile of 120 grit sandpaper?
5. How many people proceed without getting the 120 grit profile and have further success with the end epoxy results?

I can post pictures of the current state of the floor tonight if that helps. Thanks in advance, this is driving me nuts...

-Travis

 

[doordoor]

I just Diamabrushed my 3 car garage yesterday with the HD prep tool you listed. I was able to get a 100 grit finish after going over it 4 times (lots of water) It ground off all the cream the masons had worked on for smooth top. I am now down to where I see the sand in the concrete. My PPG amercoat 2 recomends a 60 grit surface. I am not sure where to go from here. The concrete is 1 year old and nothing has ever gotten on it. I am going to grind the edges today and put the Epoxy down next week, go back and get the prep tool is my suggestion.

 

[Okolowicz]

I would check other HD locations. Maybe your area is different but in my area the locations that carry the Diamabrush have both. The biggest problem I found was that most locations did not have them because they were broken. Of the 12 Home Depot stores near me only 2 had working Diamabrushes.

Also, the employees are not always knowledgeable so, make sure you ask the requisite questions to ensure they have the correct one (Prep Tool).

 

[Zmw]

I just experienced a similar event. I rented the diamabrush and it definately got the top layer of my garage floor off, but not 120 grit or even close. My floor is 30 yrs old, stains were really bad so the floor looks great but I am also concerned about the profile.

I grinded for 5-6 hours on a 460 sq ft garage.

I watched a youtube video and HD said the diamabrush is the correct tool for grinding concrete and applying epoxy. I spoke to a random customer that had done it a few times for the same application as well.

I am going to etch my surface in hopes that it will add to the grit of the surface. But, it is pourous and soaks up water pretty well.

 

[Turbotboz]

I just experienced a similar event. I rented the diamabrush and it definately got the top layer of my garage floor off, but not 120 grit or even close. My floor is 30 yrs old, stains were really bad so the floor looks great but I am also concerned about the profile.

I grinded for 5-6 hours on a 460 sq ft garage.

I watched a youtube video and HD said the diamabrush is the correct tool for grinding concrete and applying epoxy. I spoke to a random customer that had done it a few times for the same application as well.

I am going to etch my surface in hopes that it will add to the grit of the surface. But, it is pourous and soaks up water pretty well.

which wheel from above did you use?

 

[gobble]

I also used the Diamabrush and my opinion was that it didn't seem to do nearly as much as I expected. In like 5 hours I collected less than a 5 gallon bucket of concrete dust. Everyone on here said, however, that was enough to do the job.

 

[Zmw]

I used the brush in the second pick, with many diamond pads on it. It cleaned my extremely dirty floor well and a ton of dust come off, but not a very gritty surface. maybe closer to 200-250 grit if I had to guess.


After I chisel all the concrete patch out of my expansion joints, I hope etching will add to the grit. I also need to clean a few times after etching with TSP and hope that additional dust comes off and. Than I will patch a few spots, than its epoxy time.

What a frustrating project...

 

[munkey]

Grinding is tougher than some people make it out to be, and the results are quite variable depending on the (condition/makeup/hardness) of the concrete. I've ground a couple different floors and the results were radically different. The first floor required tremendous pressure to achieve any profile whatsoever, and the next one had a surface that seemed to just melt away with with the slightest pressure and left a great profile (and a ton of dust.)

I think that the goal of 120 grit sandpaper-like texture is close to impossible to achieve on certain floors, considering time constraints, experience, and the tools available for rental/DIY. IMO, forget about the grit comparison altogether... there is no point in beating yourself up about it. Obviously you can't have a slick, glossy surface, but if you've put in a reasonable effort, opened the pores up the best you can using the correct equipment, and can pass the water absorption test without beading, then I would move forward to the coating stage with confidence. That's just my take, but I'm skeptical that pouring gallons and gallons of acid on a tough-to-grind floor is really helping your cause, and it might be hurting it if you are unable to properly remove the residue and reaction byproducts.

 

[Zmw]

Munkey - Thanks for the response.

Let me know your thoughts - I was going to use a pump sprayer (for weeds) to lightly acid etch the floor because I need to acid etch my sidewalls that I am going to epoxy as well.

Is going over the entire floor lightly with acid and nuetralizing with TSP or baking soda helpful? harmful? At this point, I just want it done right since I have put a ton of time into this venture.

Thanks

 

[Edger]

Welcome to concrete preparation, professionals can experience the exact same thing.
The second Diamabrush is the one you should have used, but the first one should have worked anyway, perhaps better, depends. It appears your floor is very hard which is not usually porous too, but it can happen.
The sandpaper analogy is misleading because that is what you want for acid etching - small rough particles across the surface, but with diamond grinding it is the exact opposite which is a flat surface with millions of scratch marks.
I think you have done a good job and probably enough to coat. Just in case, I would neutralise and flush out thoroughly.
Your main test is if water beads. If not it is good to go. To reassure yourself get a magnifying glass and try to see the surface finish which should have some mechanical profile like sandpaper or scratches or both in different places.
My guess is your floor is very, very hard and will be difficult to grind unless it is done with a wet slurry which is another option. Go back to the rental of the Diamabrush and ask for another free day with the correct tool. Use it wet and keep a mud slurry for maximum grinding. Trouble is it still might not do much. Rest assured you have done very well in your efforts.

 

[AlphaGarage]

Many prep jobs don't make it to 120 grit. With our primer, BondTite 1101, the key is to get the concrete to the point where it absorbs water evenly, even if it's not at the ideal texture.

Be careful with grinding and then acid etching. If the grind opens up the concrete to where it readily absorbs liquid, then there's the possibility that the acid solution will soak in to the point where it's tough to fully neutralize, and you don't want to coat over a floor that has hot acid present.

Edger brings up a good point that we always suggest... When you go to the rental yard be very specific and tell them what you need the tool to do - in this case roughen up concrete to 120 grit. Depending on the tools and media they have they should know what combo will do the trick. If it doesn't you have a good point to request another combo without incurring the full rental charge again.

 

[HoustonGarageFloors]

Yes, they gave you the wrong attachment, the masking tool really won't cut it on bare concrete. You said that you acid washed the floor, but did you power wash it afterwards? Acid washing only burns the concrete to a brittle crust so that you can knock it off with a power washer afterwards. If you acid wash a floor without power washing it and then you apply a floor coating, you are in for a nightmare, because you just coated over very burned and crusted concrete that is begging to be knocked loose. If you did not power wash the floor, then you need to do this next; you may be surprised to see what a difference this makes. If you acid washed correctly, then power washing should knock loose several gallons of sand and reveal a profile.

Acid washing correctly: Acid will not penetrate oil stains, so these need to be soaked and scrubbed with a heavy degreaser first. You will need about one gallon of muriatic acid per every 50 sq ft of concrete to achieve a profile. Yes, this is a lot of muriatic acid. Diluting it 1:1 is correct. Acid only effectively loosens concrete upon impact. You can not simply dump the acid in the middle of the floor and let it spread out, because it will only effectively burn the area in the middle of the floor where the acid water poured out of the bucket and hit the concrete. You have to start in the back of the floor and slowly pour out the acid onto the floor as you walk across the surface from left to right, then right to left, as if you were mowing the lawn.

Power wash it if you haven't already. If you have already power washed the floor, acid wash it again as outlined above and then power wash it again... You will get a profile.

 

[pauloman]

conventional DIY acid etching could get you in real trouble with you community and your better half. It will kill your grass/lawn, and city not happen if it gets into the storm drains/water treatment plants etc.

Typically muriatic acid is used at 10% (normally sold at 33% at hardware stores. The fumes will damage any near by exposed metal (your your work tools!)

 

[Turbotboz]

Thanks for the help so far guys . Few things worth noting, this is new concrete with no oil or tire marks. The muriatic acid I used was from Lowes (31%) and then mixed 1:1. I used a garden sprayer, however I did not use a gallon for ever 50sqft. All the home Depot stores within 1.5hrs claim to only have the wrong wheel....

I did a water bead test tonight, some did bead on the surface but eventually soaked in. How long should that take, or should there be zero beading? I'm trying not to focus on the profile as much anymore as I should the absorption or water bead test. It seems that should dictate a proper surface.

I've yet to power wash the floor, so I plan to tackle that tomorrow. If that doesn't get a profile, I will try to acid etch it again (since it cheaper then renting a $200 grinder) followed by a power wash. That's plan A.

Plan B. **** it up and rent the edco grinder from United rentals. The salesman assured me it would take the concrete down to 120 grit profile.

I do have some reservations about etching again after grinding like Munkey said. Has this been an issue in the past?

Travis

 

[munkey]

I didn't mean to try to scare you away from a useful procedure -- if it needs to be done, then it needs to be done. I pictured a scenario where you did a good job grinding the surface, and water is soaking in immediately with no beading... but you were going to continue doing extra work because the 120-grit-sandpaper phrase was resonating in your head even though it might not be achievable on your surface. (I know because I've been there...)

Let us know how the power washing goes. Go slowly and try to cover the entire surface, it can really make a big difference. It can also be tricky; after water starts spraying everywhere, it can be tough to tell exactly which spots you've really blasted properly, and which are just incidentally wet. Also, keep in mind that you might have to wait for it to dry a bit before you can properly analyze the results -- don't be discouraged if you can't tell a radical difference the minute you've finished the pressure wash.

 

[Turbotboz]

Update:

I havent had much time lately but I was able to power wash the floor. I managed to get quite a bit of the grinding residue off and the floor does appear improved. BUT- there is still practically no profile and it still fails the water bead test.

With that being said- How much water should be used when doing this test? I searched with no luck. To date, I've just been wetting my hands and flicking it randomly on the ground below. Then I observe the obsorbtion up close. Currently water still beads for a few minutes. How fast should the waster obsorb? Am I doing this right?

Assuming I'm doing the above test right. I'm going to rent the Edco grinder from United Rentals thurs evening and be done with this headache. The salesman gave me the option of diamond blades or grinding stones. The stones come in 24, 36, 60, and 80 grit options. I'm assuming I need the diamond blades, thoughts/opinions?

Thanks again,

Travis

 

[Edger]

Just a guess, but if the water absorbs after a while it should be suitable for epoxy. Water on a urethane or epoxy coating will not absorb at all. If you flick the same water on pavement or other concrete you get a comparison of absorption.

I wonder why your slab is so tight, it sounds like it is a good pour, good strength, well finished, I hope so because the other alternative is that they added a chemical to the mix for waterproofing. I do not want to alarm you about that, it is probably not the case but you could perhaps check with the builder.

Being hard, you will find diamond grinding great for the first 10 mins only until the diamond segments polish, then it will slow down and polish the slab rather than cut it. To prevent this happening grind wet creating a mud slurry to keep the diamonds open which means enough water for that, but not enough to wash the slurry away. The slurry cools the diamonds and acts like an abrasive to keep them cutting.

Here is a link to an explanation of how diamond segments become polished (glaze over). http://www.situp.com.au/Grinding Hard Concrete.html
This article does not talk about wet grinding described above, but it gives you the information and what to look for to tell if the diamonds are glazed.

 

[retfr8flyr]

I just finished Sunday grinding my floor with the HD Diamabrush setup. I fond that my floor has various hardness areas, some of the floor ground easily and some if it didn't. Some areas would grind easily, with lots of dust and some would hardly show any effect, with very little dust. I spent about 12 hrs of actual grinding time on the floor. I have about 1000 sq-ft in my garage and I probably picked up about 6 gallons of dust with my dust catcher, shop vac setup. I don't have the 120 grit feeling on floor but water quickly absorbs into the floor everywhere I checked it, so I think it will be fine.

 

[Turbotboz]

Well- Its done! The garage floor project is finally complete!!!!

After another grinder fiasco (this time from United Rentals), I decided the floor was good enough to coat. Water absorbed evenly, but it wasn't the best looking surface. Due to all the previously mentioned problems, a friend of mine (also on here) convinced me to use a primer from Legacy. All I can say is I am VERY glad I did. The primer covered great! there were a few thin spots but the end result exceeded my expectations. Thanks for all the advice and help received!

As expected- Progress pictures below.

Staging my mixing area (rain was expected for the next week)



Day 1 = Primer on.




Flakes divided evenly into 6 bags. Turns out I only need two bags... (PM me for free flakes, just pay for shipping)


Day 2 AM = Base coat w/ flakes. (sorry for the poor lighting)





Day 2 PM = Clear Coat




Product Opinions: Epoxy-coat product went down perfectly, as did the Legacy primer. One thing to note- we did use measuring cups, I didn't trust the sticks. I also tried to back-roll the primer after 10 minutes and it seemed to pull it back up. As a result, I rolled the primer in one direction and then immediately back-rolled perpendicular- which turned out great. The clear coat spread VERY easily, nearly sliding across the surface. It was also difficult to see when applying as expected. SPIKED SHOES ARE A MUST- I cant imagine how anyone can do their floor successful without them.


Overall I am very happy with the end result. I have a few bugs that sacrificed their lives to the garage floor gods but I couldn't be more pleased. Thanks again to all contributing members. Now I need to decide if I'm going to paint before I move everything in...

Travis

 

[LegacyIndustrial]

Grinding is tougher than some people make it out to be, and the results are quite variable depending on the (condition/makeup/hardness) of the concrete. I've ground a couple different floors and the results were radically different. The first floor required tremendous pressure to achieve any profile whatsoever, and the next one had a surface that seemed to just melt away with with the slightest pressure and left a great profile (and a ton of dust.)

I think that the goal of 120 grit sandpaper-like texture is close to impossible to achieve on certain floors, considering time constraints, experience, and the tools available for rental/DIY. IMO, forget about the grit comparison altogether... there is no point in beating yourself up about it. Obviously you can't have a slick, glossy surface, but if you've put in a reasonable effort, opened the pores up the best you can using the correct equipment, and can pass the water absorption test without beading, then I would move forward to the coating stage with confidence. That's just my take, but I'm skeptical that pouring gallons and gallons of acid on a tough-to-grind floor is really helping your cause, and it might be hurting it if you are unable to properly remove the residue and reaction byproducts.

 

[thrasherx]

Awesome job, TurboTBoz.

 

[Mystic_Cobra]

Floor looks great. Is there a grinding tool that will take off a half inch of concrete? My floor has a big hump in it.

 

[pauls_workshop]

Floor looks great. Is there a grinding tool that will take off a half inch of concrete? My floor has a big hump in it.

The same diamond grinding wheels discussed can do it, but it will take an hour or so on that spot. Dewalt makes really good double row 4.5" and 7" wheels. Even Harbor Freight has a cheap 4.5" wheel (while I love HF for most things people recommend on the GJ HF thread, I don't know that I would trust my life to their diamond grinding wheel, but some have said it is fine). You can look up the dewalt on amazon. The diamabrush would prob be fine too for this I would think if you have the right one. - Paul

 

[Turbotboz]

Yeah any handheld grinder with a diamond wheel should do the trick.

To provide a ~30 day update. Floor is awesome. Tons of compliments, even from our home builder himself. My only regret is not using some type of light duty non-skid on the entire floor. I cant express how slippery and dangerous the floor is when wet... Every member of my family has already slipped a few times...

Thanks to everyone again for the advice and support along the way. So glad I found GJ!

Travis

 

[Mystic_Cobra]

If I'm going to sand/grind the whole 500 sq ft floor including removing a hump that's roughly 6 square feet (and a half inch high) plus remove hardened liquid nails from carpet squares that covered the floor...is there a big machine that I can rent that will make this take a couple hours vs a couple days? My knees and lower back are sore just thinking about this.

 

[LegacyIndustrial]

Edco machine with stripserts tooling.

or... swing machine with Diamabrush Mastic Removal tool.

 

[ConfidentlyInept]

I swear this is a basic question but can not find an answer anywhere on this internet thingy.

I'm currently ripping up tiles downstairs (crappy DIY job) and will be getting a concrete grinder to get the adhesive off and level/prep the concrete.

How smooth does the concrete have to be for an epoxy coating? I'm expecting a lot of swirl marks left over from the grinder and am unsure if an epoxy coating will cover swirl marks, like some kind of levelling compound, or if it is just a paint and therefore the concrete will need to be somewhat smooth.

 

[Turbotboz]

I swear this is a basic question but can not find an answer anywhere on this internet thingy.

I'm currently ripping up tiles downstairs (crappy DIY job) and will be getting a concrete grinder to get the adhesive off and level/prep the concrete.

How smooth does the concrete have to be for an epoxy coating? I'm expecting a lot of swirl marks left over from the grinder and am unsure if an epoxy coating will cover swirl marks, like some kind of levelling compound, or if it is just a paint and therefore the concrete will need to be somewhat smooth.

I wouldnt worry about the swirl marks. The important thing is making sure it obsorbs water and there is no film or powder of the surface after grinding.