For cleaning cast iron hubs, black pipe threads and rusty hangers by hand, buy the Forney 70504 long-handle carbon steel wire brush. For heavy rust and scale on a grinder, use the Forney 72759 4 in knotted wire wheel on a 4-1/2 in angle grinder with a 5/8-11 spindle. Switch to stainless, like the Forney 70521 brush or 72805 wheel, on stainless or aluminum or in wet spots, and use a brass brush on brass and copper parts.
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A wire wheel is only as good as the grinder behind it. Our angle grinder guide covers the tool, and our cast iron pipe cutter guide covers the cut you make before you clean the end.
Quick picks
| Pick | Type | Wire | Best plumbing job | Exact purchase |
|---|---|---|---|---|
| Forney 70504 | Hand brush, long handle, 3 x 19 rows | Carbon steel | Cast iron hubs, black pipe threads, rusty straps | Check Forney 70504 on Amazon → |
| Forney 70521 | Hand brush, long handle, 3 x 19 rows | Stainless | Stainless and aluminum, wet areas | Check Forney 70521 on Amazon → |
| Forney 70527 | Detail brush, plastic handle, 3 x 7 rows | Brass | Brass valves, unions and fittings | Buy from a Forney dealer; we found no in-stock new Amazon listing on October 14, 2026. |
| Forney 72759 | 4 in knotted wheel, 5/8-11 | Carbon steel, .020 in | Heavy rust and scale on cast iron and steel | Check Forney 72759 on Amazon → |
| Forney 72805 | 4 in knotted wheel, 5/8-11 | Stainless, .020 in | Stainless pipe and parts, wet locations | Check Forney 72805 on Amazon → |
| Milwaukee 48-52-5070 | 4 in crimped wheel, 5/8-11 | Carbon steel | Lighter surface cleaning | Buy from a Milwaukee dealer; we found no in-stock new genuine Milwaukee listing on Amazon on October 14, 2026. |
Hand brush rows and wire type come from the Forney scratch brush listing (forneyind.com). Wheel specs come from the Forney 72759 (forneyind.com), Forney 72805 (forneyind.com) and Milwaukee 48-52-5070 (milwaukeetool.com) product pages.
BEST HAND WIRE BRUSH · CARBON STEEL
Forney 70504: long-handle carbon steel wire brush
Choose it when you need one brush for the truck. The 70504 is a carbon steel scratch brush with a long handle and 3 by 19 rows, per the Forney listing (forneyind.com). The long handle keeps your hand away from sharp hub edges and rough concrete. It cleans old dope out of male threads on black pipe before you re-make a joint, and takes scale off hangers and strut.
Skip it on stainless steel, aluminum, chrome or brass trim. Carbon steel bristles scratch soft metals and can leave steel bits on stainless that later rust. Use the stainless or brass brush.
BEST FOR STAINLESS AND WET AREAS · 3 X 19 ROWS
Forney 70521: stainless long-handle wire brush
Choose it when the work is stainless steel, aluminum or in a wet spot like a sump pit or crawl space. The 70521 is the stainless version of the long-handle 3 by 19 row brush, per Forney (forneyind.com). On its stainless wheel page (forneyind.com), Forney says stainless wire is recommended for corrosion-resistant or non-ferrous metals such as stainless or aluminum, or when the brush is used in a wet environment. Stainless bristles that break off will not rust into orange stains.
Skip it if you only clean cast iron and black pipe. Carbon steel cuts rust faster and costs less to replace.
BEST DETAIL BRUSH · BRASS, 3 X 7 ROWS
Forney 70527: brass detail brush for fittings
Choose it when you are cleaning threads on a brass valve, a union seat or the threads on a hose bibb. The 70527 is a small brass brush with a plastic handle and 3 by 7 rows, per the Forney listing (forneyind.com). Brass is softer than steel, so it cleans without chewing up brass threads. Forney also sells the same brush in stainless (70525) and nylon (70526).
Skip it for cleaning copper pipe and fittings before soldering. Use a fitting brush and emery cloth made for that job; see our solder and flux guide.
Buy the 70527 from a Forney dealer; we found no in-stock new Amazon listing for it on October 14, 2026.
BEST WIRE WHEEL FOR GRINDER · 20,000 RPM MAX
Forney 72759: 4 in knotted wire wheel for heavy rust
Choose it when you are cleaning a lot of rusty cast iron or steel. The 72759 is a 4 in twist-knot wheel with .020 in high carbon steel wire and a 5/8-11 arbor, rated for 20,000 RPM, per the Forney product page (forneyind.com). Forney lists it for removing weld scale, spatter and heavy corrosion. Knotted wheels hit harder than crimped ones, which is what you want on a crusty cast iron spigot before a no-hub coupling goes on.
Skip it on thin-wall pipe, threads you plan to reuse, or anything plated. A knot wheel can round over threads and cut through coatings fast. Use a hand brush or a crimped wheel there.
STAINLESS GRINDER WHEEL · 20,000 RPM MAX
Forney 72805: stainless knotted wheel
Choose it when you need a grinder wheel for stainless steel pipe, brackets or tanks. The Command PRO 72805 is a 4 in knotted wheel with .020 in stainless wire, a 5/8-11 arbor and a 20,000 RPM maximum, per the Forney product page (forneyind.com). Forney recommends stainless wire for stainless and aluminum and for wet locations.
Skip it for general rust on cast iron. The carbon steel 72759 does that job for less.
LIGHTER CLEANING · CRIMPED
Milwaukee 48-52-5070: 4 in crimped carbon steel wheel
Choose it when you want a gentler wheel for surface rust, old paint and general cleanup. Milwaukee lists the 48-52-5070 as a 4 in radial crimped carbon steel wheel with a 5/8-11 thread for general purpose surface cleaning and conditioning. It fits 4-1/2 in or 5 in grinders with 5/8-11 spindles, per the Milwaukee product page (milwaukeetool.com).
Skip it if you need to cut through heavy scale. Milwaukee says it is not capable of etching. A knotted wheel is the better choice there.
Buy the 48-52-5070 from a Milwaukee dealer; we found no in-stock new Amazon listing for the genuine Milwaukee wheel on October 14, 2026.
How to choose a wire brush
Match the wire to the metal
- Carbon steel: cast iron, black steel pipe, galvanized hangers and strut. Most aggressive and cheapest.
- Stainless steel: stainless and aluminum, and anything in a wet place. Forney recommends it for both.
- Brass: brass and bronze valves and fittings, where steel would scratch.
- Nylon: plastic fixtures and finished surfaces. Not a wire brush, but Forney sells it in the same handle.
Knotted vs crimped wheels
Knotted (twist-knot) wheels twist the wire into stiff bundles. They hit hard and cut heavy rust and scale; Forney lists its 72759 for heavy corrosion. Crimped wheels use loose, wavy wire. They are softer and better for general surface cleaning, as Milwaukee lists for the 48-52-5070. A stringer bead wheel, like the DeWalt DW4925 (dewalt.com), is a narrow knotted style that DeWalt lists for cleaning, deburring and surface preparation.
Arbor size and speed
Every wheel on this page has a 5/8-11 threaded arbor. That screws directly onto the spindle of a standard 4-1/2 in or 5 in angle grinder. Check two numbers before you spin it: the wheel’s maximum RPM, printed on the wheel or its package, and the grinder’s no-load RPM on its nameplate. The wheel’s rating must be higher. The Forney wheels here are rated for 20,000 RPM.
Hand brush or wheel?
Use a hand brush for threads you plan to reuse, for brass, and for small jobs. Use a wheel when you have many feet of rusty pipe or a hub full of scale. A wheel is fast, but it removes metal and coatings fast too.
Safety with wire wheels
Wire wheels throw wire. Bristles break off and fly at high speed, even from a new wheel. Wear safety glasses plus a face shield, gloves and long sleeves. Keep the grinder’s guard on. Start the grinder pointed away from you and anyone else, and let it run for a few seconds before you touch the work.
- Old lead joints: cast iron hub joints in older homes are often lead and oakum. Do not wire wheel or grind the lead. Cut outside the hub and treat lead debris as hazardous.
- Gas pipe: cleaning the outside of black gas pipe is fine. Taking apart or re-making gas joints needs the gas off, a leak test and, in most places, a permit and a licensed pro.
- Dust: brushing rust and old paint makes fine dust. Work with air moving and wear a dust mask.
After cleaning black pipe threads, use fresh thread sealant or cutting oil as the job calls for. Our pipe threading oil guide covers oil for cutting new threads.
Wire brush FAQ
What wire brush is best for cleaning cast iron pipe?
A carbon steel brush. By hand, use the Forney 70504 long-handle 3 x 19 row brush. For heavy scale, a 4 in knotted carbon steel wheel like the Forney 72759 on an angle grinder is faster.
Should I use a stainless or carbon steel wire brush?
Use carbon steel on cast iron and black steel. Use stainless on stainless steel and aluminum and in wet places. Forney recommends stainless wire for corrosion-resistant and non-ferrous metals and for wet environments.
What is the difference between a knotted and a crimped wire wheel?
A knotted wheel twists the wire into stiff bundles and cuts heavy rust and scale. A crimped wheel uses loose, wavy wire for lighter surface cleaning. Milwaukee says its crimped 48-52-5070 is not capable of etching.
What size wire wheel fits a 4-1/2 inch angle grinder?
A 4 in wheel with a 5/8-11 threaded arbor. Milwaukee says its 48-52-5070 fits 4-1/2 in or 5 in grinders with 5/8-11 spindles. Make sure the wheel’s maximum RPM is higher than the grinder’s no-load RPM.
Can I use a wire brush to clean copper before soldering?
Use a fitting brush and emery cloth made for copper instead. A steel wire brush can scratch and contaminate the copper. A brass brush is fine for cleaning brass fittings and valve threads.
How we chose
This is a document-based comparison from a licensed plumber’s point of view. We read the Forney, Milwaukee and DeWalt product pages for the exact brushes and wheels on this page, and picked the wire types and sizes a plumber uses for cast iron, black pipe and fittings. We favored makers that publish wire type, arbor and maximum RPM. Sources and linked listings were read October 14, 2026; sellers and availability change. We do not publish prices or claim hands-on testing. More about our selection method and Plumbing Picks.
Primary sources
- Forney scratch brushes listing (forneyind.com): 70504, 70521, 70525, 70526 and 70527 wire type, rows and handle.
- Forney wire brushes listing (forneyind.com): wheel and cup brush item numbers and wire types.
- Forney 72759 knotted wire wheel (forneyind.com): 4 in, .020 in high carbon steel, 5/8-11 arbor, 20,000 RPM, uses.
- Forney 72805 stainless knotted wire wheel (forneyind.com): 4 in, .020 in stainless, 5/8-11, 20,000 RPM, stainless and wet use.
- Milwaukee 48-52-5070 crimped wheel (milwaukeetool.com): 4 in carbon steel, 5/8-11, grinder fit, general cleaning.
- DeWalt DW4925 stringer wire wheel (dewalt.com): 4 in, 5/8-11, .020 in carbon stringer.
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