Last Updated on October 6, 2026 by Umar Farooq
Choosing the best concrete grinder for paint removal is a decision about the dust collector, not about the grinder — and the specification that settles it is a single line in a federal regulation that almost nothing on the shelf quotes.
That line sits in OSHA’s respirable crystalline silica standard for construction, 29 CFR 1926.1153, in the table of specified exposure control methods the trade calls Table 1. It is free to read, it names the handheld grinder explicitly, and it does what no product listing does: it puts a number on the extraction.
I read 139 listings to find out how many repeat it. One does, and that one is a shroud for a circular saw.
Table 1 Writes the Control Down as an Airflow
Row (xii) of Table 1 is titled “Handheld grinders for uses other than mortar removal”, which is you, your angle grinder and a diamond cup wheel on a painted slab. The row offers two routes, and they are not equivalent.
The first route is water. “For tasks performed outdoors only: Use grinder equipped with integrated water delivery system that continuously feeds water to the grinding surface”, plus “Operate and maintain tool in accordance with manufacturer’s instructions to minimize dust emissions.” Required respiratory protection on that route, under four hours in a shift and over four hours in a shift alike: None. None.
The second route is extraction, and it is the one the market sells. “Use grinder equipped with commercially available shroud and dust collection system”, the same operate-and-maintain line, and then the sentence the whole page turns on:
“Dust collector must provide 25 cubic feet per minute (cfm) or greater of airflow per inch of wheel diameter and have a filter with 99% or greater efficiency and a cyclonic pre-separator or filter-cleaning mechanism.”
Outdoors, on that route, the respirator column reads None and None. “When used indoors or in an enclosed area”, it reads None for up to four hours and APF 10 beyond four hours — an assigned protection factor of ten, which is a properly fitted half-mask (29 CFR 1926.1153, Table 1).
Three things in that specification deserve pointing at.
The filter requirement is not HEPA, and the standard is careful about it. Table 1 asks the dust collector for a filter of “99% or greater efficiency”. The same regulation defines HEPA separately, in its definitions paragraph, as “a filter that is at least 99.97 percent efficient in removing mono-dispersed particles of 0.3 micrometers in diameter” — and reserves that word for other rows. For a walk-behind floor grinder used indoors, Table 1 wants “a HEPA-filtered vacuum to remove loose dust in between passes.” For the handheld, 99% and a way of keeping the filter clean. So the marketing word and the regulatory word are not the same word, and the regulator knows the difference even where the aisle does not.
The pre-separator is an either/or. A cyclonic pre-separator *or* a filter-cleaning mechanism. Not both. That matters, because the filter-cleaning mechanism is the thing a lot of extractor listings actually publish.
The four-hour clock is cumulative. Paragraph (c)(3) says that where the combined total of all Table 1 tasks in a shift runs past four hours, every task takes the over-four-hour respirator. Three short jobs in one afternoon are one long job as far as that column is concerned.
And the duty, as written, is the employer’s: paragraph (c)(1) puts the obligation to “fully and properly implement the engineering controls, work practices, and respiratory protection” on the employer, for each employee engaged in a listed task. The owner of the paint-removal method ladder on this site makes the point that nobody regulates your garage. True — and the usefulness of Table 1 to a homeowner is not that it binds you. It is that it is the only place anyone has written down how much airflow the shroud needs, and it is the number the shelf is silent about.
Divide the Airflow by Twenty-Five and You Get a Wheel Size
Twenty-five cfm per inch of wheel diameter is a specification you can run in either direction, and running it backwards is the most useful thing on this page. The arithmetic is mine; the figure is the regulation’s.
| Cup wheel diameter | Airflow Table 1 asks the collector to provide |
| 4-1/2 in. | 112.5 cfm |
| 5 in. | 125 cfm |
| 6 in. | 150 cfm |
| 7 in. | 175 cfm |
| 9 in. | 225 cfm |
Now the other half. Sixteen of the thirty-eight dust extractors and shop vacuums I read publish an airflow figure, and they cluster tightly: 125, 138, 140, 142, 148, 150, 151, 153 and 157 cfm. Bosch’s VAC090AH and VAC140AH both publish a maximum 150 cfm. DEWALT’s DWV010 publishes 150. Makita’s VC4210L publishes 148. Metabo HPT’s ASR 35 ACP publishes 157, which is the highest portable figure in the census.
Divide 157 by 25 and you get 6.28 inches. Not one portable extractor on this shelf publishes enough airflow for a 7-inch cup wheel.
Which would be a footnote if 7-inch were a specialist size. It is not. Of twenty-one diamond cup wheels in the census, ten are 7-inch, and 7-inch grinder kits, shrouds and grinder sets run all the way through it, because 7 inches is what people reach for when the job is a floor rather than a doorway. The shroud market goes further still: one universal shroud advertises that it “Fits most 6-inch to 9-inch angle grinders”, and a 9-inch wheel asks the collector for 225 cfm — nearly half again the best figure anybody here prints.
Two caveats, because a check is only publishable with its limits attached.
The published figure is a maximum at the machine — motor on, hose off, bag empty, filter clean. Table 1 asks what the collector must *provide*, through fifteen feet of anti-static hose, a fleece bag and a filter that is loading as you work. So the gap opens up under load rather than closing. That cuts against the shelf, not for it.
And one outlier is not a counter-example. A two-stage cyclone dust collector in the census publishes 1,240 cfm, which clears every row of that table. It is a 3 HP, 230 V stationary machine for a woodworking shop. Airflow of that order exists; it just does not come on casters.
The exception that proves the rule is the one listing that does the division for you. DEWALT’s FLEXVOLT 60V dust extractor publishes this, in its own first bullet: *”125 CFM of the dust extractor provides OSHA Table 1 Compliant Solutions for up to 5-inch Tuckpointing and Surfacing Applications when paired with an appropriate dust shroud.”* One hundred and twenty-five divided by twenty-five is five. DEWALT has run the arithmetic, landed on a wheel diameter, and published the ceiling rather than the capability. That is one listing out of 139, and it is the only one in either census that tells a buyer what its machine *cannot* keep up with.
What the Box Says Against What the Rule Specifies
Here is the census. Sixteen search phrasings on the grinder side — concrete grinder, angle grinder dust shroud, diamond cup wheel 7 inch, walk-behind concrete grinder, epoxy coating removal grinder and eleven more, including five led by brand name — returned 149 results and 101 distinct listings. Five phrasings on the extraction side returned 38 more. Every count below comes from the pass taken without a minimum-ticket filter, because that filter quietly drops the trade-channel listings and three of the five it dropped here name a shroud in their titles.
| What Table 1 specifies | Grinders and cup wheels (101) | Extractors and vacuums (38) |
| A commercially available shroud | 31 use the word | — |
| Any dust collection or extraction at all | 37 | 38 |
| A dust port or hose dimension | 2 | 3 |
| An airflow figure in cfm | 1 | 16 |
| A filter efficiency percentage | 0 | 10 |
| A filter-cleaning mechanism | 0 | 23 |
| A cyclonic pre-separator | 0 | 2 |
| The word HEPA | 2 | 28 |
| The word silica | 6 | 8 |
| Any reference to OSHA or Table 1 | 2 | 11 |
| A respirator or a dust mask | 0 | 0 |
| Integrated water fed to the grinding surface | 0 | — |
Read the first column downwards and watch the specification evaporate. A third use the word “shroud”, which is the easy half of Table 1’s sentence. Then the numbers go to pieces. One listing in 101 publishes an airflow figure, and it is a vacuum sold alongside a grinder. Nothing in that column gives a filter efficiency, a pre-separator or a filter-cleaning mechanism, because those live on the other half of the pairing and nothing points across.
Two listings in 101 publish a dimension for the dust connection. One walk-behind grinder names “a 1.97 in / 50 mm vacuum port”. One 7-inch shroud names a “Standard hose fitting” and gives its outside diameter as 1-7/16 inches. Everything else says universal. “Universal vacuum hose connection locks onto the tool.” “Fits most vacuum cleaners.” “All standard vacuum valves can be easily connected.” Universal is a promise about geometry; the regulation is asking about volume.
And the column that is genuinely zero in both directions: not one listing of the 139 mentions a respirator or a dust mask. Not the grinders, not the cup wheels, not the shrouds, and not the HEPA extractors whose entire reason for existing is the particle that makes a respirator necessary.
Worth knowing what one whole sub-class in that column actually is, because the titles mislead. The multi-head machines in the 3800 W bracket — “4-head”, “dual-port dust-free system”, “zero dust leakage” — are angle-grinder motors on an extended handle with a hood over them, and Table 1 cares about the wheel and the shroud rather than the handle length. They take the handheld row’s arithmetic and, indoors past four hours, the handheld row’s half-mask.
The second column is a different trade talking. Twenty-eight of thirty-eight extractors say HEPA, ten quote a filtration percentage, twenty-three publish a filter-cleaning mechanism, sixteen publish an airflow. Eleven mention OSHA by name and two name Table 1 itself. The extraction aisle speaks the regulation fluently and the grinder aisle does not speak it at all — and a reader standing in front of the grinders has no way of knowing that the answer is two aisles over.
One more number out of that, because it is the awkward one. Of the shrouds the census found, the single one whose listing mentions the silica rule — “Complies with OSHA silica laws and EPA Regulations for point-of-origin dust containment”, on a universal attachment for 6-to-9-inch grinders — sits below the floor this site links above. So does every other angle-grinder shroud in the census bar two. The part Table 1 names first is the part nothing here will let me hand you a button for, and I would rather say that than route you to a bundle so a link works.
Both Tool Classes Print “Dry Only”
Table 1’s no-respirator route is water, and it is the route the assignment for this page expected to end on: wet-grind, or hire something with proper dust control. The census says the first half of that is not purchasable here, and two manufacturers say it in their own words.
Bosch’s operating instructions for its 5-inch concrete surfacing grinder state the intended use as surface grinding of “mainly mineral materials such as, for example, concrete, stone, marble and poured flooring without the use of water“, and then carry a boxed warning: “Do not use water or other cooling fluid with this tool” (Bosch CSG15 operating/safety instructions). The best-documented dry concrete grinder on this shelf forbids the one control that takes the respirator column to None.
The walk-behind says it too, and more briefly. The 1400 W walk-behind concrete grinder in the census publishes, inside the bullet about its motor: “Note: For dry grinding only, not for wet grinding.” Table 1’s row (xiii) for walk-behind milling machines and floor grinders is the only grinder row in the whole table that permits an integrated water system indoors — no outdoors-only qualifier, no respirator in either duration column, with the instruction to “use a HEPA-filtered vacuum to remove loose dust in between passes” when working in an enclosed area. That is precisely the machine a garage floor wants, and the one you can buy tells you not to put water in it.
Which leaves exactly one wet tool in 101. A 4-inch wet stone polisher, with a “flexible splash guard and 3-hole water system”, Class A GFCI protection, a water shroud and seven diamond polishing pads from 50 to 3000 grit. Its own copy says the water “blocks harmful silica dust”, which is the only time the mechanism appears on a tool listing anywhere in this census. It is also not a paint-removal tool: polishing pads at 700 to 3000 rpm burnish a surface, they do not take a coating off it, and Table 1’s handheld wet route is outdoors-only regardless. I am not linking it, because it does not do this job — but it is the proof that integrated water delivery is a thing a factory can build and sell, and the proof that nobody builds it into the tool you would use.
So the shelf sells one of Table 1’s two routes and prohibits the other, and the one it sells is the one with the arithmetic in it and the half-mask at the end of it. If the job is a whole garage floor, the wet walk-behind is a hire-counter machine — and hiring one is not a consolation prize, it is the only version of this job Table 1 lets you do indoors with nothing on your face. Whether your bay can take the water at all is a drainage question before it is a dust one.
The Manual Carries the Respirator the Listing Drops
Zero of 139 listings mention respiratory protection. I assumed that meant the market had nothing to say about it. It is the opposite: the absence is in the retail copy, not in the documentation, and the manufacturer’s own manual is blunter than anything I expected to find.
From the same Bosch instruction manual, in the additional safety warnings:
“This tool must be used with Respiratory Protection sufficient to block dusts including silica from concrete cutting. N-95 rated masks minimum or full respirator protection for the operator and others in the work area.”
Note who that covers: not the operator, but *the operator and others in the work area*. Whoever is holding the other end of the extension lead is inside the sentence. Two more from the same pages: “Dust collection is required with a vacuum or other suitable dust collection system for concrete/masonry applications”, and, in the operating section, “This tool must only be used with a dust extraction system. In addition, always wear approved dust mask.” Required, must, always. Then the one piece of guidance where the manual runs out of numbers: “Always make sure the vacuum cleaner that you use is designed for extraction of masonry dust.” Designed for. No cfm, no filter class. The maker publishes the requirement and declines the figure, and Table 1 publishes the figure and declines to name a product, so the buyer is the only party in the transaction holding both halves.
Bosch’s own catalogue page for that grinder does publish the connection, incidentally, and names “most other 35 mm hoses” as compatible. That number does not appear on the retail listing, which is the pattern worth internalising on any tool purchase: check the manual before you conclude a specification does not exist. It usually exists. It is just not for sale.
Now the part I have to be straight about, because a page that demands a respirator it will not sell you is a page with a hole in it. I cannot link you the half-mask. I searched for one twice. At the floor this site links above, “respirator half mask” returns nothing and neither does “p100 respirator” — the entire category of respiratory protection sits below the floor, which means the one item Table 1 names for indoor work past four hours is an item I can describe and cannot put a button under. The useful thing I can tell you is what to ask for: an APF 10 elastomeric half-mask with P100 filters, fit-checked before you start rather than after you notice the taste. The same APF 10 class turns up in the field data on wet abrasive work, where water cut measured silica by a factor of about four and still left it over both recommended limits, and the silica-free blasting media that look like the gentle option still attract OSHA’s type CE airline respirator and positive-pressure helmet. The pattern across all of it is the same: changing the medium or adding the water changes which respirator, not whether.
The Best Concrete Grinder for Paint Removal Is Half an Extractor
Here is my one strong opinion on this page and it will cost somebody a shopping list. The grinder is not the purchase. The extractor is. Every grinder in this census will take paint off concrete, because a diamond cup wheel removes the top of the slab and the paint goes with it — that mechanism is not in dispute and the method ladder that rates its dust as severe already has it right. What varies between listings is not whether the tool cuts. It is whether anything in the transaction publishes the number that keeps the cutting out of your lungs. So buy for disclosure, pair by arithmetic, and size the wheel to the airflow you can actually prove.
For the 5-inch pairing where the arithmetic closes: DEWALT’s FLEXVOLT 60V dust extractor. It is the only listing of 139 that converts Table 1’s specification into a wheel diameter and publishes the limit — 125 cfm, up to 5 inches, “when paired with an appropriate dust shroud”. It also carries automatic filter cleaning with dual filters, a HEPA filter in the box, and a conditional compliance line that names the consumable it depends on: it meets the EPA’s renovation, repair and painting rule for HEPA vacuums “when used with the included HEPA filter”. Conditional claims are a good sign. They mean somebody in the building read the rule.
Its real limitation is the one DEWALT itself prints. Five inches is the ceiling, so this is the wrong extractor for the 7-inch cup wheel half the wheel census is selling, and the listing gives no filter efficiency percentage to check against Table 1’s 99%. It is battery-powered with an 8-foot hose, and nothing quantifies runtime at full suction.
For a corded 6-inch ceiling with the filter numbers on the page: Bosch’s VAC090AH. This is the single best-specified listing in either census and the only one that answers every part of Table 1’s dust-collector sentence in its own words. A maximum 150 cfm. A HEPA filter that “captures 99.97 percent of particles at 0.3 microns or larger”, which is the regulation’s own HEPA definition read back verbatim. And a filter-cleaning mechanism published as an interval rather than a claim: it “cleans the filter every 15 seconds”. Table 1 asks for a pre-separator or a filter-cleaning mechanism, and this is the second one, with a number on it. Its compliance sentence is also the most carefully worded in the census, and I come back to that below.
The limitation is arithmetic again. One hundred and fifty cfm is 6 inches of wheel, and it is a maximum rather than a delivered figure, so a loading bag and a long hose eat into it. Fit a 7-inch cup wheel to this and you are outside the specification with nothing in the pairing to tell you.
For the tool half, where documentation beats copy: Bosch’s CSG15 5-inch concrete surfacing grinder. The listing itself is unremarkable — eight bullets about amps, rpm, sealed bearings and a spindle lock, with a “comprehensive guard/shroud system” and not one word about silica, airflow or a port size. Its manual is where everything is, and everything quoted two sections above came out of it: mandatory extraction, N-95 minimum for the operator and bystanders, a vacuum designed for masonry dust, and a flat prohibition on water. At 5 inches it pairs with either extractor above and the division works out.
The limitation is that you would never know any of that from the page you buy it on, which is a fair criticism of the listing rather than the tool, and the water prohibition means this grinder can only ever take Table 1’s dry route. Add the dedicated-tool caveat: this is a concrete grinder, not an angle grinder that also grinds concrete, so it will not cut steel or take a flap disc.
And the recommendation with no link attached, because it is the right answer. The grinder shroud whose listing mentions the silica rule — a glass-filled nylon universal attachment with a sliding front edge, for 6-to-9-inch angle grinders — sits below the floor this site links above, as does every other angle-grinder shroud in the census bar two. If you already own a 7 or 9-inch grinder, that attachment plus the best airflow you can get is a better afternoon than any new tool on this page, and steering you into a kit you do not need so a button would work would be the opposite of what this page is for. Two details decide whether any shroud actually seals, so check for both: soft brushes around the rim, and spring suspension to hold the shroud flush as the tool crosses an uneven slab. A shroud that lifts off the surface is venting into the room. Then read the next section before you believe its compliance claim.
Where a Listing Borrows the Regulator’s Authority
Eleven listings mention OSHA. Four of them claim something OSHA does not let a product claim, and the failure is identical in all four: compliance under 1926.1153 is a property of an implementation, not of a part. Paragraph (c)(1) places the duty on the employer, and paragraph (e)(3) says that an employer who “fully and properly implements the engineering controls, work practices, and respiratory protection described in Table 1” is considered to be in compliance. The controls, the work practices *and* the respiratory protection. A box on a shelf cannot supply the third one and cannot supply the implementing.
A walk-behind crack chaser prints “[OSHA COMPLIANT]” in square brackets and then gives its reasons: “Connect to a vacuum system to improve visibility, reduce airborne dust, and minimize cleanup.” Visibility, dust and cleanup. No airflow, no filter efficiency, no silica, no section number. It is also a trolley — “Angle grinder sold separately” — so the thing wearing the compliance label is a chassis with wheels on it. Reviewed, and no button: a listing that uses the regulator’s name as a feature and then lists housekeeping benefits is telling you it has not read the regulation.
A cyclone dust separator goes further: “OSHA Table 1 Compliant: When used with a HEPA-certified CT Dust Extractor, the CT CYCLONE is in full compliance with OSHA’s Table 1 rule for silica dust.” In full compliance. This one stings, because the part is genuinely the right part — Table 1 names a cyclonic pre-separator as one of its two alternatives and only two listings in 38 offer one. But a separator cannot be in full compliance with a table that also specifies an airflow it does not generate and a respirator it is not, and it publishes no cfm of its own. Left without a button, with regret.
A certified-HEPA contractor vacuum claims “COMPLETE CONTAINMENT: Will never blow dust or pickup back into the air”, and “Complies with EPA RRP and OSHA laws and regulations concerning hazardous material pickup.” Never is a strong word about a filter with a seal in it, “laws and regulations” names nothing, and the listing publishes no airflow at all — so the one number Table 1 wants from this exact product category is the one it omits while asserting compliance in general. No link.
And the shroud below the link floor claims it “Complies with OSHA silica laws and EPA Regulations for point-of-origin dust containment.” I recommended that attachment above and I stand by it, because point-of-origin containment is what a shroud does. The compliance sentence is still wrong: a shroud is half of a control, and the other half is an airflow somebody has to supply.
Set all four against the wording Bosch chose for its extractor — a dust collection system “to help users move toward OSHA Silica Table 1 dust compliance”. That hedge is not weakness. It is the only compliance sentence in 139 listings that correctly locates compliance in the user’s setup rather than in the product, and it came from the company whose manual also tells you to put a mask on. When a maker’s legal department and its marketing department disagree about a regulation, read the manual.
Two listings I want to name for the opposite reason, having set the bar that high.
The disclosure benchmark in the whole census is a shroud for a circular saw, and it is the only listing of 139 that quotes Table 1’s arithmetic: *”SUPPORTS OSHA SILICA TABLE 1 WORK PRACTICES: use with a HEPA vacuum rated 99% filtration at 25 CFM per inch of blade. Adapts to 1-1/4 and 1-1/2 inch hoses; 1.5 inch cuff and both shields included.”* Filter efficiency, airflow per inch, two hose sizes and the cuff that comes in the box. Note the word it had to change: Table 1 writes “per inch of wheel diameter”, in the two handheld grinder rows, and this listing has carried that figure across to a blade. It supports Table 1 work practices rather than complying with them, which is exactly the right verb. And it fits a 7-1/4 inch worm drive saw, so it will not go anywhere near your angle grinder. No link, because it does not do this job — but if the standard of disclosure on this page looks unreasonably high, it is because one company has already met it.
And the walk-behind that publishes the most numbers of any grinder here still does not get a button. It is the only grinder of 101 to print a vacuum port dimension, “a 1.97 in / 50 mm vacuum port”, beside its disc diameter of “7.09 in / 180 mm” — two measurements a buyer can work with, since 7.09 times 25 is 177 cfm. Credit for that. It then prints “For dry grinding only, not for wet grinding”, which closes off the indoor water route that is the whole point of the walk-behind class, and the 177 cfm its own disc implies is above every portable airflow figure in this census. Add that it is a marketplace brand with no manual-grade documentation I could find — no spec sheet, no parts breakdown, nothing with the standing of the Bosch instructions above — and the honest advice is to take a wet one off a hire counter instead.
And one grinder is worth naming for a silence rather than a claim. A 5-inch concrete surface grinder kit from a major brand lists five features: a brushless motor, an electronic kickback brake, a power-loss reset, variable speed and a bail handle. Every one is a real safety or usability feature and not one is about dust. No failing quote is available, which is the point — there is nothing there to quote.
One last thing on the brands above. Power tools are the category where recalls run most frequently, so I checked every brand I was about to link through CPSC’s recall service before writing this section. The live one is DEWALT’s recall of 4.5-inch 40-grit T27 high-density flap discs, models DWA8280HRT and DWA8280RT, date codes 2024-36 to 2024-48 — about 17,680 units, after three reports of the ceramic cloth flaps detaching in use and three resulting injuries, with the instruction to stop using them immediately (CPSC, 3 July 2025). Nothing in this census is a flap disc and nothing linked above sits in that family — but if you own an angle grinder you probably own a box of these, so go and read the date code. The other grinder notices across these brands are model-scoped and old, Makita’s carrying the line “No other Makita grinders are involved in the recall”. One of them is worth keeping as a mechanism rather than a model number: Makita’s hazard was that “the guards on some of these angle grinders will not fully cover a hubbed grinding wheel.” A diamond cup wheel is a hubbed wheel, and a shroud is a guard you have chosen to replace. Fit matters at both ends.
FAQ
What is the best concrete grinder for paint removal?
For a patch, a step or a doorway, a 5-inch dedicated concrete grinder with an integrated shroud paired with an extractor that publishes at least 125 cfm, because that is the only size where the published airflow on this shelf satisfies the 25 cfm per inch of wheel diameter that OSHA Table 1 asks of the dust collector. For a whole floor, a walk-behind with a wet system — which means the hire counter, since the walk-behind machines sold here publish “for dry grinding only”.
How much vacuum do I need for a concrete grinder?
Twenty-five cubic feet per minute of airflow per inch of wheel diameter, plus a filter of 99% or greater efficiency and either a cyclonic pre-separator or a filter-cleaning mechanism. That is Table 1’s specification for a handheld grinder. Run the division for your wheel: 5 inches wants 125 cfm, 7 inches wants 175, 9 inches wants 225. Then check whether your vacuum publishes a figure at all, because most shop vacuums do not.
Do I need a HEPA vacuum to grind concrete?
Table 1 does not require HEPA for a handheld grinder — it asks for 99% filter efficiency, where the same regulation defines HEPA separately as at least 99.97% efficient at 0.3 micrometres. HEPA appears in the grinder rows only for the walk-behind machine used indoors, which is told to use a HEPA-filtered vacuum between passes. In practice most extractors sold for this work are HEPA anyway, so the question that actually bites is the airflow, not the filter.
Can you grind concrete wet with an angle grinder?
Table 1 allows it, with an integrated water delivery system that continuously feeds water to the grinding surface, for tasks performed outdoors only — and on that route no respirator is specified at any duration. The problem is the hardware. Across 101 listings I found no handheld concrete grinder with an integrated water feed, and the best-documented one carries a boxed warning not to use water or any other cooling fluid with it. Wet grinding is a different machine, not a different technique.
Will a diamond cup wheel damage the concrete under the paint?
Yes, and that is the mechanism rather than a side effect — the wheel takes the top of the slab off and the coating leaves with it. That is fine on a floor you are about to coat and permanent on a floor you wanted to keep. The same trade-off is why spot-grinding a field of overspray dots swaps a stipple in paint for a stipple in etched cement paste, and why conservation guidance on masonry says power tools such as grinders should never be used on a face you intend to look at afterwards.
Do I need a respirator in my own garage?
The regulation binds employers, not homeowners, so nothing compels you. The manufacturer is less relaxed than the regulator: Bosch’s own manual for its concrete grinder says the tool “must be used with Respiratory Protection sufficient to block dusts including silica from concrete cutting”, with N-95 masks as the minimum, and extends that to “the operator and others in the work area”. A garage with the door up is an enclosed area for Table 1’s purposes, which is the one case where the handheld row puts a half-mask in the column.
Hire the Walk-Behind, Buy the Extractor
Table 1 asks the dust collector for 25 cubic feet a minute per inch of wheel diameter. Divide the best airflow figure published by any portable extractor in this census by that number and you get a wheel 6.28 inches across, which is smaller than the cup wheel half this market sells. Divide the airflow DEWALT itself publishes and you get five inches exactly, printed as a ceiling, by the one company that did the sum in public. Everybody else sells you the word “universal” and leaves the volume to you.
So the purchase order comes out backwards from the way the aisle is arranged. The extractor is the component with the specification, the shroud is the one Table 1 names and the one nothing here will let me link, and the grinder is the one everybody shops for and the one that varies least. Size the wheel to the airflow you can evidence, read the manual rather than the listing, and if the job is a floor, the machine Table 1 lets you run wet indoors is a machine you take back on Monday.
Measure the wheel before you measure the slab. The slab tells you how long the job is; only the wheel tells you how much air the job needs, and the number that matters most on this page is one you can work out with a tape measure and a division.
