Epoxy floor prep/floor finish

[fstbusa]

Grind/acid/both??

Broom finish vs trowlled smooth finish

Everything ive read says that grinding is best and acid is second.

What is discussed less is the finish of your floor before you start. Obviously a broom finish is better but what if you have a smooth finished floor?

Are you stuck with(or highly recommended to) grinding the floor vs acid prep?

My floor is new(3 months old) with a smooth finish and I'm concerned that an acid wash will not create enough of a profile for the epoxy to adhere to.

What are everyones thoughts or experiences.

 

[OldNeons]

I'm not an expert, but all my research and the 2 floors I've done, say GRIND IT! Most of the horror stories I have read involved "I didn't grind it, but I ............." It's a days work and $100-150 rental to do it right. How excited are you about stripping failed epoxy and THEN getting to grind it and buy all new material? Just sayin....

 

[mrobins297aaa]

I did two floors over the last 8 years, the first one was "u-coat it". the concrete was a little over two months old and the last one I did was "Epoxy coat". the concrete was about 6 months old. I didn't grind either one just acid washed them and they both came out excellent. they both were about 2300 sq/ft......I just followed the manufacturers instructions.

 

[OldNeons]

Let's wait for some of the pros to chime in, but I'd say you've been lucky to wash two floors and have them both perform satisfactorily. Curious if any pro installers do jobs with avid wash and no grind?

 

[Edger]

I think a smooth floor is definitely best and I would acid etch without hesitation. Grinding creates too many other problems - OK if you do that for a living, but no good for DIY unless you are lucky.

First you need to create a porous surface and a little profile. That is easy if you use strong enough acid mix. Min. should be 6 water to 1 acid. Do a test. Mix three acid strengths in small plastic cups at 6:1, 4:1 and 3:1, pour small amounts onto the floor around the edge and watch what happens. It should fizz nicely, if not make sure you leave it for 5-10 mins.

Second you need a powerful pressure washer 3,000 psi+ and you need to blast very close to the floor. I would go over it in one direction, then change 90 degrees.

After that I doubt you will have problems, I am sure if you test it the next day it will be profiled and absorb water easily, not like a sponge, just absolutely no beading.

I manufacture grinding equipment and have been grinding floors for nearly 20 years so I know how it can be a pain for the DIY. The biggest problem is matching the right grinding segments to the hardness of the floor so it will work correctly. Rental shops do not do that so you take a big chance. Second is what you fill the tiny airholes with that can cause outgassing and bubbles in the coating. Third is how you grind all the low spots without significant grinding shoulder marks which will show through the coating.

If you want to grind without those problems the new Diamabrush system will be the closest answer because diamonds are not in metal segments so they are always sharp and can grind soft or hard floors. If you can rent a floor buffer with a diamabrush under it then that is the best because the flexible diamond blades will get into the low spots too and they do not agressively grind down the surface unless you sit there in the one spot. Then you still have the edges to do. Next choice if you cannot rent a buffer would be a hand grinder with a Diamabrush head.

My opinion is that diamond grinding with metal bond segments is great for professionals, but too often a nightmare for DIY. Acid etch has less problems if you get a fizz and you thoroughly water blast it after.

 

[mrobins297aaa]

for the record both of my floors were a trowel finish. (smooth finish)

 

[mrobins297aaa]

Let's wait for some of the pros to chime in, but I'd say you've been lucky to wash two floors and have them both perform satisfactorily. Curious if any pro installers do jobs with avid wash and no grind?

Well I don't think i got lucky, I just followed the manufacturers instructions.
Is there another way you should do it?

 

[OldNeons]

Maybe I am wrong, hope some of the regulars can confirm their daily practices. All I have heard from most professionals is to grind. Didn't mean to diminish your work or the end product, glad it is working well for you. To me the risk of time and materials is too great to not grind, but that is a choice each of us can make.

 

[mrobins297aaa]

Maybe I am wrong, hope some of the regulars can confirm their daily practices. All I have heard from most professionals is to grind. Didn't mean to diminish your work or the end product, glad it is working well for you. To me the risk of time and materials is too great to not grind, but that is a choice each of us can make.

I understand where your coming from, its not a easy fix if you screw it up.
But with "Epoxy coat" they actually give you the acid wash in there kit to use. They have a pretty good track record of success with there system. there a lot of satisfied customer on this site that have used there product and method of installation. but like you said everybody has to make then own choices, thats what research is for

 

[mrobins297aaa]

as for pro's Edger is a pretty knowledgeable guy on the subject........read a lot of his post before i did my last floor.

 

[dcs Inc]

Guys, I do this this for a living and train and certify other installers the proper procedures on resinous flooring applications. Acid etching is the last thing I'd suggest on profiling a slab of concrete. If you want to do it correctly at least grind the floor. Shot blasting is the ideal prep but requires a little knowledge on the operation of the equipment.

A little research on the INTERNET will provide you with the information on the procedures of prep and application. Diy'rs like hearing that all they need to do is squirt a little muriatic acid on the floor, let it dry and roll out their epoxy. Big wrong. Here's a map of concrete hardness across the country.



This will tell you the diamond matrix needed to correctly grind your concrete. Mostly a 30-40 grit diamonds do a good job. The more segments, the less down pressure of each segment. A 24 segment 7" turbo cup grinder will leave less cup marks than a 12 segment. The single row segmented will chew a hole into the concrete if left in one place. Larger rental machines (I would rather use a 10" single head edco than the duel head) with the dyma Serts or the diamond segmented plate work OK. Down pressure on these are your friend. Fast? no. A 7" diamond grinder with a 24 segment turbo cup will be as fast or faster than the edco's. Some rental companies have a 7" stand up model that guys use for edging. These work fine.

If compelled to acid etch do so after grinding. Profile is everything! Give your concrete some teeth so the epoxy will adhere properly. Use a primer first!

 

[LegacyIndustrial]

Gene:
Good to point out that the smaller head with weight on it will reveal weak concrete better than the dual head. We have seen the results of of a good epoxy stuck to weak concrete recently on this board and it is not pretty.

 

[Falcon67]

FWIW - I have done two power trowel finish floors using a strong etch, wash, dry and epoxy. Knock on medium soft aggregate, no issues with either floor - although the new one has only 8 months of use so far. The other was a hard working floor for 12 years and is now retired as someone's game room.

 

[Edger]

Unfortunately the hardness map has very little to do with grinding concrete unless you want to expose the aggregate. It is an indicator of stone aggregate hardness not of concrete hardness.

To diamond grind prepare a floor the diamond segments are mostly grinding concrete paste, it is only when you go below the paste that you hit aggregate and then the map may be of some use.

Concrete is specified at different hardness values in the batching plant for different uses so slabs vary a lot (nothing to do with aggregate hardness). On top of that some concrete finishers add water to the mix which softens the concrete, so the hardness varies some more. On top of that the final finishing can be done with too much bleed water on the surface which will make it soft on top and harder underneath, or it can be power trowelled to a shiny harder finish making it harder on top and softer underneath.

A professional will have a variety of diamond segments for different hardness values and can change those if the floor changes. As Gene mentioned the number of diamond segments on a wheel can also make a difference although this is not the real answer to grinding hard concrete, soft bond is the solution. When you rent a grinder you have to take pot luck with what you get and that is not a criticism of rental companies, just a fact.

For those who have not read about the right segments for hard or soft concrete here is a link http://www.situp.com.au/Grinding Hard Concrete.html

That is why I recommend acid etching as a viable alternative for diy and as can be seen from above posts many people have had great success with that method.

 

[dcs Inc]

Sure, lets do a pull test on some of these acid etched floors and compare them to one that was properly prepped. Different hardness values when ordering concrete? Are you talking compressive strengths? That's figured by cement bag content. Of course there are additives for high early strength but that doesn't affect the final hardness of the concrete. It's actually the sands of the region and then the aggregate. Florida uses shells which makes for a soft concrete. Yes you use hard bonds for it. Indiana is a medium soft so I use a medium bond. Especially for polishing. The average cup grinder you purchase are medium to hard. A heavily glazed finish requires either changing up the bond matrix or it takes a little longer to cut through it. Depositing metal off the power trowel blades really causes a slower grind. I went the extra mile when stocking diamond cups for prep work. I have the soft, hard, 16 grit, 20 grit, 30-40 grit, 60 and 80. 12 segment, 24 segment, S segment, V segments..... ALL of them are used on Indiana concrete. Some want a faster grind though it eats up the segments faster. A lot of the specialty cups are for glues, epoxies, paints and every other piece of **** that people put on floors.

The rental companies attempt to find a happy medium in their tooling supply. Most supply a medium hard diamond matrix. Decorative concrete rental companies will have just what you need.

Edger you are correct in your statement of different finishing practices. But simple thinking will tell a guy if the concrete is grinding fast, move the grinder faster... If it's grinding slower... humm? Scratching too hard and leave a curfs mark, grind it out and blend it in.

Your suggestion of using muriatic acid will cause many more problems with improper profiling than trying to steer these guys in the correct standard of prepping a floor for an epoxy application. Over flooding concrete with water is bad. Power washing is horrible unless you have plenty of time to let it dry.

I think I read your hot link awhile back. Can't really remember it. I'll take a look later. The one thing you have to remember is, "If you keep the iron in one spot it will burn your clothing" That's really not tough to pull into grinding. Now how is a guy to know just how much acid is enough? Well if fizzed..... that doesn't tell anything. How much of that stuff do you want to burn your lungs.... I know, concrete dust isn't good for you either. (Wet grinding is really the way to go but you have to deal with the clean up).

Oh, now we have the "safe" acid products. Wow, I wont even get into that dance. Here's the facts: Scratch the hell out of your concrete. I don't care how you do it. It must have a profile that will allow the epoxy to adhere to. Short cut it in any way and you take the chance of failure.

 

[Edger]

Oh, now we have the "safe" acid products. Wow, I wont even get into that dance. Here's the facts: Scratch the hell out of your concrete. I don't care how you do it. It must have a profile that will allow the epoxy to adhere to. Short cut it in any way and you take the chance of failure.

Sorry Gene, but I disagree with your comment above about profile.

Profile in my opinion has only a little to do with adhesion and you are convinced it is everything. Absorption is the key to proper adhesion, not profile!

I redid enough jobs by people who hammered the hell out of concrete to get adhesion, but they failed to clean away the dust fully or failed to remove the oil enough and the epoxy broke away from the rough profile easily within 12 months.

Without the ability of the epoxy to soak into the surface all the profile in the world will not help. Acid etch, shot blast, grind or whatever the main purpose is to break down the surface so that the epoxy will soak in. You should add that to your teaching notes.

 

[dcs Inc]

When did we start talking about a dirty floor? Oil? Of course epoxy wont stick to it. Are you telling me when one grinds a profile it doesn't open the surface? I guess I should state the Mr. Obvious that you should clean it also..... I think you should start telling these folks to make sure they neutralize the concrete when they drizzle a little acid on it. An incorrect surface pH will cause major problems. Doesn't matter how deep of a hole you attempt to burn into the surface.
Giving these guys a thumbs up on this short cut is wrong.

 

[dcs Inc]

Edger, we are not talking of anything different here. We are disagreeing on how to achieve it.

 

[Edger]

Gene, your opening in your first post of this thread knocked acid etching as a viable alternative. In other posts you have done the same and you keep scaring people, but I know from your posts that you have next to no experience with it.

I do have lots of practical experience with it and I have found it to be a great preparation method in the right circumstances. I used to do it as a cheaper alternative because I had the water jet equipment to quickly and thoroughly clean the floors after. My first preference was diamond grinding, but I never had a problem with acid etching adhesion on jobs and I never neutralized the acid and I always flooded and blasted the floors with water and coated the very next day or at most two days later.

As you can see from many posts here guys have had great success with it. Epoxy coat and other companies promote it, guys use those products and have success. Sure this forum sees lots of problems, but what has been pointed out before is that all the successes are not mentioned here, most guys come to avoid problems or to fix them.

There are as many acid etch problems as water problems, bubbling problems and grinding problems. Acid etch does not really stand out and when it does it is usually because of doubts about the finish after etching not the peeling coating.

I try to give folks some advice when I know I have personal experience on the subject.

 

[drinkmoresake]

Let me start out by saying I am a newbie here and am NOT a pro installer. Just want to pass along that I had great success with using the product manufacured by Surface Gel Tek to etch my floor. The stuff is not cheap (about $80 per gallon, not including shipping) but it was very easy to work with. The acid is suspended in a gel solution that you just roll onto the surface (even vertical ones). The end result was a nice even profile with the feel of 100 grit sand paper. I would not hestitate to use this stuff again.

 

[Garage Flooring]

Let me start out by saying I am a newbie here and am NOT a pro installer. Just want to pass along that I had great success with using the product manufacured by Surface Gel Tek to etch my floor. The stuff is not cheap (about $80 per gallon, not including shipping) but it was very easy to work with. The acid is suspended in a gel solution that you just roll onto the surface (even vertical ones). The end result was a nice even profile with the feel of 100 grit sand paper. I would not hestitate to use this stuff again.

I spent some time talking to these guys today and talking to one of our installers as well. He grinds everything, but this looks like it may be a promising option for some DIY installs (no previous paint, coatings, additives or sealers)

We are going to have him check it out further

 

[dcs Inc]

Sorry for the late reply. I had to teach a class today. Edger I acid etch a lot of floors for our overlay products. It's not for profiling but to shock the slab and then neutralize for a pH neutral surface atmosphere to apply our hybrid cementitous overlay products. This is after a good spiral grind or shot blast on interior overlay applications. I also know how difficult it is to break a glazed troweled surface with muriatic acid. I know how uneven the burn is. I know that the acid wont cut rubber, paint, glue or any of the many sealers on the market. It doesn't do anything for oils, brake fluids, even car shines, wax or any silicone based products. If one lets the acid dry on the surface it creates salts that become very difficult to remove and affect the bond of epoxy. You don't neutralize?

Have you ever took a strong whiff of acid? It shuts down the bronchioles making it difficult to breath. The chemical burns throw you right into acute bronchitis. This is serious stuff. Oh, you recommend diluting it heavy.... Oh that will do a lot of profiling. Wear protective clothing, wear a protective mask that will save your lungs. Now we have to get rid of this ****. Wash it down the street? Down the drain or storm sewer??? There are laws on this stuff. It's a hazardous waste product. Even if it's been diluted.

Lets add another factor. You are degrading the surface of your concrete. Hydrochloric acid (muriatic acid is a brand name) eats the cement content around the sands in the surface paste. You are weakening the surface everytime you apply it to get the profile you are wanting? What profile are you going for and how do you know you have it evenly over the entire surface. This type of application is an open door for short cutting one of the most important steps in applying epoxy.

One other thing. I don't here anyone suggesting testing for moisture vapor transmissions. Is that not a big deal? Class starts at 7am. got to get some sleep.

Gene, your opening in your first post of this thread knocked acid etching as a viable alternative. In other posts you have done the same and you keep scaring people, but I know from your posts that you have next to no experience with it.

I do have lots of practical experience with it and I have found it to be a great preparation method in the right circumstances. I used to do it as a cheaper alternative because I had the water jet equipment to quickly and thoroughly clean the floors after. My first preference was diamond grinding, but I never had a problem with acid etching adhesion on jobs and I never neutralized the acid and I always flooded and blasted the floors with water and coated the very next day or at most two days later.

As you can see from many posts here guys have had great success with it. Epoxy coat and other companies promote it, guys use those products and have success. Sure this forum sees lots of problems, but what has been pointed out before is that all the successes are not mentioned here, most guys come to avoid problems or to fix them.

There are as many acid etch problems as water problems, bubbling problems and grinding problems. Acid etch does not really stand out and when it does it is usually because of doubts about the finish after etching not the peeling coating.

I try to give folks some advice when I know I have personal experience on the subject.

 

[drinkmoresake]

One more tip related to acid etching that smeone shared with me. To help further neutralize the "runoff" when you wash the stuff out of the garage pour baking soda just outside the door (use a lot and kind of make a slurry). Seemed to work pretty well for me.

 

[CamarosRus]

Gene, After doing three calcium chloride tests on my slab I had 8.5# readings.

I am having difficulty concluding which brand name product(s) is the best
value for either a DIY application or maybe hire a expereinced man/contractor

Yes I will have to shot blast or grind

Yes I want to topcoat with flakes or solid color if flakes are out of my budget (???)

Live in Auburn , WA if anybody has local contacts

Thanks,

 

[thegarageguy]

When I got into the biz, I was taught to acid wash floors. I was taught in Sunny every fricken day San Diego California. I now know that concrete in NY and NJ is a complete different animal.

All of my floors failed in my first year in business except for one. I redid them all on my dime. The Company who taught me is now out of business.

For guaranteed results, we diamond grind and or shot blast.

 

[Garage Flooring]

When I got into the biz, I was taught to acid wash floors. I was taught in Sunny every fricken day San Diego California. I now know that concrete in NY and NJ is a complete different animal.

All of my floors failed in my first year in business except for one. I redid them all on my dime. The Company who taught me is now out of business.

For guaranteed results, we diamond grind and or shot blast.

I think all of us are in agreement that grinding or shot blast is the best solution and works regardless of prior coatings, etc. In most cases it would also be best to hire a pro. Unfortunately, not every case is best case. While we currently require our customers to grind their floor, we are always looking for a better DIY solution.

 

[slickgt1]

Let these guys argue it out. If you want a DIY project, go with tile. No grinding it, no acid anything, no worries. If you want Epoxy, search for someone really skilled at the job, and be ready to pay up. That's my $.02

 

[Garage Flooring]

I wanted to follow up on this conversation. We received some samples of the TEK Gel product for testing purposes. We had our installation team who ALWAYS grinds use the TEK GEL product.

This is what we were told:

I had one of my guys test the TEK GEL with good results. We used the Profiling solution and he told me it did make an acceptable surface for coating. Draw backs- acid. Smell. fumes. The product did work well and no grinding was necessary.​

We are adding it as an approved preparation process for untreated/ uncoated concrete for our products.

Its expensive when you compare it to muriatic acid BUT it is much safer and much more controlled. It also neutralizes with water

http://www.garageflooringllc.com/acid-etching-garage-floor-coatings-prep/

 

[drinkmoresake]

I used the Tek Gel HD-24 "Pre-Grind" solution which is a little more aggressive and is suppose to give a profile close to 80~100 grit. I think their "Profiling" product produces a feel similar to 120 grit. Either way, a good way to produce a very even profile. For those who are interested their website is http://www.etchingconcrete.com/ . Not the greatest website but some good info on the product.

 

[Garage Flooring]

I used the Tek Gel HD-24 "Pre-Grind" solution which is a little more aggressive and is suppose to give a profile close to 80~100 grit. I think their "Profiling" product produces a feel similar to 120 grit. Either way, a good way to produce a very even profile. For those who are interested their website is http://www.etchingconcrete.com/ . Not the greatest website but some good info on the product.

They have a couple of different strengths. Our concern is the stronger material that yields a rougher surface is going to create a profile that is going to affect your coverage.

 

[drinkmoresake]

Good point. I think they suggested the stronger one to me since I was planning on doing multiple coats of epoxy, can't remember exactly. Anyway, good stuff (except a little $$).

 

[Frank Dreb]

Hm. Good discussion here. Just saw a Epoxy coat DIY floor that was installed over a smooth floor just using a muriatic acid etch. Holding up fine after 3 years. That said, I don't want to take any chances.

If you have a broom finish is grinding still necessary? Not sure what I'd be gaining by grinding down a broom finish.

 

[dcs Inc]

You will level any high spots saving money by not having to apply another thick mil coating to fill in the trip spots left. In this case I would acid etch and NEUTRALIZE the concrete after giving it a light grind to even out any high spots produced by the broom.
You don't want to remove the broom texture, just level out. Make sure after you have NEUTRALIZED the concrete, to wash it several times with just thew fan spray on a hose. Use ammonia to neutralize. Cut you muriatic acid about 4-1 and make sure you get a decent fizz every where. Keep the floor wet untill you neutralize it. A little pre wertting of the floor will help.
As long as there isn't any cure n seals, paints, or any other **** on the floor that the acid wont touch, you will be fine. Figure a little high on your primer coat or vapor barrier primer coat to do a good fill in on the texture.

Oh, give it a FEW days before you apply your epoxy to completely dry.

 

[mes5278]

I want to post this in this thread so that others who are reading this can benefit from my misfortune. Based on this (and many other threads ) I too decided to grind my floor. I still highly recommend this method. However I do have the following warning/advice

DON"T USE A CUP STONE

A diamond cup wheel is fine but the stones can come apart and cause serious injury. The stone was old, was being abused and probably spun too fast. I am not blaming the stone. To be honest I don't care if it was the stone, me or just the garage demons that made it fail. I won't be using one of these ever again.

Here is what my leg looks like today after using a cup stone to grind the edges of my concrete floor.



Quite frankly I consider myself VERY lucky.

 

[regancc]

So I am not sure if weighing in here with a question is appropriate or should I start my own thread?

My question is: How should I prepare my floor if I previously painted it with the epoxy paint from HD? I don't like the finish or the color and want to do a nice coat and fill the expansion joints for a smooth and shiny surface (with some shark skin additive for non-slip traction).

Do I have to strip the old paint (it is holding up pretty well with the exception of one small area that is chipped up...not sure how)?

Also, after reading other posts in another thread about expansion joints and paint cracking due to expansion/contraction from temp changes, I am concerned about filling them, but I love the smooth look and no dirt gets in them when filled and painted over.

So, if I need to start another thread, I will, but could use some advice from you experts.

My floor is 11 years old and is about 900 sf.

Thanks.

Chip

 

[dcs Inc]

Ouch mes5278..... Good advice on what not to use. Those lessons hurt sometimes. Looks as it you hit something hard and the something won. Good that wasn't near an eye or other tenderer parts.

 

[CamarosRus]

I had my 29' x 45' slab shotblasted by a pro contractor prior to installing my recently completed epoxy system. Machine was mfg by BLASTRAC with about an 18" wide path. Machine left "cornrows" (formed by overlaps) that I had read about in my research.

Two epoxy vapor barrier coats were laid down, full broadcast of chips, coat of epoxy clear over chips and finally top coat of CPU (urethane). I dont know know total mil thickness of my floor. I can still see cornrows in the finished installation.

My expert installer (that I hired by the hour) says shot blaster was too agressive and I should have received a less agressive blast for my "thin mill floor" versus ??? floor install.

I havent tried to take pics yet of the cornrows showing through all the layers.

Your comments and opinions of what could have been different.

Thanks

 

[Spaggs]

I just diamond grinded my floor in prep for epoxy. Swept up and then vacuumed the left over dust. Do I need to pressure wash it as well or is it ready to go?

Spaggs

 

[CamarosRus]

I'm no expert and sure one of them will chime in............

but I would NOT introduce any water onto your concrete.

After several sweeping sessions and vacumning I would wipe down with denatured alcohol if anything at all.

I had my floor shot blasted and applied my epoxy (vapor barrier) right onto vacumned concrete. I did install a full broadcast chip system so the importance of super clean on my first coat didnt seem to be an issue. I did get a lot of minute misc "stuff" trapped in my first coat.

 

[dandan111]

Hope you are feeling better mes ,bet that hurt like hell!