Beginner: etch confusion and venting advice

[epoxonyourhouse]

Long-time lurker, first time poster. I've done a ton of searching and reading and could still use some beginner advice. I have a coated slab floor in basement (looks like concrete paint) that I want to grind off and do epoxy. Have to fix some cracks and divots too. I'm at the starting stage of doing moisture tests and I plan to rent a single-disc grinder and some sort of dust collection system from Sunbelt, and some sort of grinder for the corners the big grinder can't reach. Couple specific questions where I'm seeing conflicting info in my search results here:

1. Etching: A concrete contractor told me to grind, etch, then use a kit (e.g., Armor Proxy) of primer, epoxy and topcoat. However, many kit instructions (I've read quite a few now) say to grind, clean and then apply primer to the porous concrete, with no mention of etching. Do I need to etch after grinding, or just vacuum and clean after grinding? (And what do people like to clean with if I'm not etching?)
2. PPE/ventilation: I'm way less concerned about my ability to do the job than I am about making beginner mistakes with my health. I have a 3M half-mask with P100s, will wear goggles and ear protection - might even just splurge and get a full-face respirator. However, I'm still freaked about the dust, especially with the mystery paint. Is the respirator and dust collection sufficient, or should I also use a fan out of a window and/or through the garage door? Do you use ducting with the fan? Is this overkill? Even reading on here, I'm not clear if setting up fans would actually make things better or worse. Ideally it would move any dust the collection system didn't catch outside, but I could also see it agitating air in the room and making it a dusty hellscape.
3. Disposal: this is a pretty dumb question but I've never seen it done. How do you safely transfer concrete dust from dust collectors to bags for disposal? Just keep your respirator on, go outside and dump/shovel?

Thanks for answering my ******* questions!

 

[FJ4FUN]

You are on the right track and these are not "*******" questions!

1) Due to existing coating you will need to grind. Etching is NOT needed (in fact it is highly discouraged) after grinding. Simply use the same HEPA vac that you are going to rent with a floor wand attachment to remove any residual dust. IF dealing with soft concrete that continues to shed dust you may consider rinsing with water (not high pressure) and sucking up with a wet/dry vac then allow it to dry prior to priming.

2) YES, on PPE and don't skimp on quality equipment! Given that this is a basement with, I'm assuming, limited access, you may be stuck with having to use a smaller walk-behind grinder. Whatever the case, rent the heaviest grinder that you can get into the space along with an appropriately sized HEPA dust extractor setup such as:


plus:

plus:


(from Sunbelt Rentals)
Exhausting free silica dust to the outside of your home is ineffective and NOT very neighborly...

3) You'll note that the dust extractor above automatically bags the dust for easy, clean, disposal.

After all that work you'll want to make sure to apply a top quality epoxy system and, considering that it's an interior basement application, one with no VOCs... For that, check out one of our systems at AlphaGarage. If you have any additional questions about prep, application or moisture mitigation feel free to contact me anytime...

 

[epoxonyourhouse]

This is great, thanks a lot for your help. I've read a lot of your posts along the way. I'm sure this will not be the last series of questions I have. Had no idea bad idea to vent. WE're in a rural area w/ far-away neighbors (ca. 350 ft away) but good point, can still blow over...

My vehicle size is more of a bottleneck than basement access. Basement goes to garage with a double-door (all same slab) and driveway on same level...i just don't know how big a grinder I can get into SUV.

 

[FJ4FUN]

This is great, thanks a lot for your help. I've read a lot of your posts along the way. I'm sure this will not be the last series of questions I have.

Bring 'em on....

 

[epoxonyourhouse]

Probably looking at something like this - any major pitfalls there besides it taking longer? The one you pictured required 230V which I don't have, plus this one (or a similar 9") will actually fit in the car with the vac and be liftable by a couple middle aged folks with bad backs...



Also, the 5" DeWalt handheld get in corners but any tips for the the little corner wedge beyond the reach of the 5" wheel and shroud? I don't even care about such a tiny spot not being finished to the same standards as the rest of the floor, esp. as corners of room won't even be visible with the framing I'll be doing, but I am concerned if it would affect adherence for surrounding coating lifting if it's not properly prepped?

 

[FJ4FUN]

You're right, I thought it was a 115V machine. I'm pretty sure they do have a 115V variant of the single head Edco but that still won't address the transpo concerns. I don't have personal experience with the Husky and have heard mixed reviews. The bottom line is that you will need something that you can transport down the stairs and, if I remember correctly, the Huskys can be easily broken down into two pieces making it easier to move around. It may take you a bit longer but so be it.

Getting the last bit ground on inside corners won't make or break the coating. If your concerned just get in there and make sure any existing paint is roughed up with a wire brush or an oscillating tool.

EDIT: Also, consider renting a p/u truck to move EQ given that stairs are not a factor... a properly sized dust extraction along with the grinder will likely challenge your SUV space.

 

[epoxonyourhouse]

You're right, I thought it was a 115V machine. I'm pretty sure they do have a 115V variant of the single head Edco but that still won't address the transpo concerns. I don't have personal experience with the Husky and have heard mixed reviews. The bottom line is that you will need something that you can transport down the stairs and, if I remember correctly, the Huskys can be easily broken down into two pieces making it easier to move around. It may take you a bit longer but so be it.

Getting the last bit ground on inside corners won't make or break the coating. If your concerned just get in there and make sure any existing paint is roughed up with a wire brush or an oscillating tool.

EDIT: Also, consider renting a p/u truck to move EQ given that stairs are not a factor... a properly sized dust extraction along with the grinder will likely challenge your SUV space.

Yep no stairs...and I think it's the TL-9 (Edco) they have locally. They just had that Husky photo for some reason. Handles fold down and at 81 lbs I think we can get it and the 1.5'X4' extractor in the RAV, but pickup truck would make the job easier.

Would people recommend the Lavina L14E over this? .5 less HP than the TL-9 but 14" vs 9". I wasn't sure if HP or grinder size made the bigger difference. I'm guessing the latter. Though at 130 lbs, it's probably bigger and might require a truck. I should note the "E" stands for "Edger." I can't quite figure out (even with a decent amount of G**gling) diff between "edge grinder" and just "grinder"...feel free to provide insight.

Thanks! I'm definitely asking some basic questions in the hope that having this "organizing the rental" stuff in one thread is helpful for future searches...

 

[Armorpoxy]

Great choice for the coating! That being said if you grind definitely no need to etch. Feel free to contact us directly with any guidance needed.

 

[FJ4FUN]

Yep no stairs...and I think it's the TL-9 (Edco) they have locally. They just had that Husky photo for some reason. Handles fold down and at 81 lbs I think we can get it and the 1.5'X4' extractor in the RAV, but pickup truck would make the job easier.

Would people recommend the Lavina L14E over this? .5 less HP than the TL-9 but 14" vs 9". I wasn't sure if HP or grinder size made the bigger difference. I'm guessing the latter. Though at 130 lbs, it's probably bigger and might require a truck. I should note the "E" stands for "Edger." I can't quite figure out (even with a decent amount of G**gling) diff between "edge grinder" and just "grinder"...feel free to provide insight.

Thanks! I'm definitely asking some basic questions in the hope that having this "organizing the rental" stuff in one thread is helpful for future searches...

The "E" in Lavina L14E stands for Electric (vs Gas/Propane). BTW, the difference between an edge grinder and a std grinder is that the edge grinder will have an opening on the side of the shroud that will expose the cutting head and allow you to grind right up against the wall. Std shrouds (grinders) will completely cover the cutting head/s to maximize dust extraction performance but will only allow the cutting head to get within +/-2" of the wall/edge so you'll have to break out the angle grinder or edger to finish it off.

As far as which one to pick it kinda depends on the job at hand. Basically the performance of the grinder ultimately comes down to the amount of weight/pressure applied to the tooling and having enough torque to cut. A 100lb 9" cutting surface will have more lbs per square inch than a 100lb 14" cutting head but, obviously, it will require more passes for a given area. Also there is a comfort factor to consider, the Lavina machines have a more sophisticated cutting head design that allows the tooling to flex in their relation to the contour of the floor so it acts somewhat like a suspension system which makes for a much smoother operator handling. The Edcos are fixed position and will beat you up a bit more as they transfer a lot more vibration through the handle. For smaller floors up to the 400sf size a single head Edco will do fine, for larger areas, at a minimum, I'd want a twin head Edco (with Advil) and when you start approaching 600sf+ a larger/heavier 20+ inch Lavina.

 

[epoxonyourhouse]

The "E" in Lavina L14E stands for Electric (vs Gas/Propane). BTW, the difference between an edge grinder and a std grinder is that the edge grinder will have an opening on the side of the shroud that will expose the cutting head and allow you to grind right up against the wall. Std shrouds (grinders) will completely cover the cutting head/s to maximize dust extraction performance but will only allow the cutting head to get within +/-2" of the wall/edge so you'll have to break out the angle grinder or edger to finish it off.

As far as which one to pick it kinda depends on the job at hand. Basically the performance of the grinder ultimately comes down to the amount of weight/pressure applied to the tooling and having enough torque to cut. A 100lb 9" cutting surface will have more lbs per square inch than a 100lb 14" cutting head but, obviously, it will require more passes for a given area. Also there is a comfort factor to consider, the Lavina machines have a more sophisticated cutting head design that allows the tooling to flex in their relation to the contour of the floor so it acts somewhat like a suspension system which makes for a much smoother operator handling. The Edcos are fixed position and will beat you up a bit more as they transfer a lot more vibration through the handle. For smaller floors up to the 400sf size a single head Edco will do fine, for larger areas, at a minimum, I'd want a twin head Edco (with Advil) and when you start approaching 600sf+ a larger 20+ inch Lavina.

Thank you for the gentle correction instead of writing "The "E" stands for "Idiot"

Great explanation and insight, esp. the weight/pressure piece of the puzzle and the ease of use between brands.

OK, a final remaining question: is there a recommended technique for mitigating the increased dust due to the suboptimal dust extraction due to the opened/retracted shroud when grinding against walls? All the solutions I'm picturing in my head are pretty much Acme Corporation level (as in Roadrunner cartoons)...e.g., have girlfriend hover nearby holding a running Shop Vac, etc.

 

[FJ4FUN]

The shrouded hand held angle grinder, like the DeWalt from Sunbelt pictured above, actually do a very good job when hooked up to the rented dust extraction unit. Only downside is that you typically can't run both the field grinder and grind the edges at the sametime. If you want to run both simultaneously then rent one of the smaller HEPAs for the hand held as well.



Unless you setup your shop vac with one of the cyclonic pre-filters they're pretty useless for dust extraction as they'll load up the filter too quickly.

 

[epoxonyourhouse]

Thanks. Have a cyclonic extractor (Oneida) but still need to build it up!