Laser-Cut Parts Finished: Powder Coat, Anodize, Passivation

The laser edge first: burr, oxide and the edge break

A laser-cut edge can carry burrs, the sharp residue left when molten metal solidifies below the kerf instead of being blown clear, and aluminum tends to burr more than other materials (source 8). Laser-cut steel also gets a very thin, hard oxide on the cut edge that typical pretreatment cleaners do not normally remove, so a coating over it has little adhesion (source 7). Reader answers on a finishing forum say the residue the laser leaves has to come off before topcoating and that the sharp edge should be rounded before powder coating, because powder coat is thinnest at an edge (source 6). That is why a "break all edges" or "deburr" callout belongs on the print of any coated part. Bare mild steel rusts when it meets water and oxygen, and a coating is what keeps them off the iron (source 5), so an outdoor steel part with no finish on the print gets a question back in the quote.

Two things to know before calling it out. A deburr callout that does not name faces can reach faces that must stay bright, so a 2B stainless face or a 5052 sheet that must stay bright is drawn "light edge break only, faces as rolled". Thin sheet and fine tabs are worth naming, so the print should say which faces and features are left alone. Write the edge condition you need, not the process: "no burrs, edges broken" gives the quote and the inspection something to check against. The steel and aluminum spokes describe the raw edge on each sheet.

Powder coat: color by number, thickness that fills holes, masking drawn on the print

Powder coat is written with a color standard and a gloss, never a color name alone. A RAL Classic number is four digits, for example RAL 9003 signal white, RAL 5010 gentian blue or RAL 7040 window grey (source 4), and a named powder line also settles a shade. A gloss band settles the sheen, and a texture note (smooth, textured, wrinkle) settles the feel. Powder is applied electrostatically and cured under heat, and it can build thicker than liquid paint without running (source 3). That build is the whole story on fit. Products Finishing puts typical powder film thickness at around 2 to 3 mils, 0.002 to 0.003 in, with the range for each powder on its technical data sheet (source 13). A close slot narrows, a clearance hole shrinks by twice the coat, and threads are masked on the print instead.

On a build-to-print order those are drawn, not discovered: the print masks the threads ("mask 4x 1/4-20 thru"), masks any datum face or grounding surface that must stay bare, and either accepts the build on clearance holes or calls them oversize. Powder coat is quoted on aluminum, steel and stainless alike, so a bracket and its stainless mate can carry the same RAL number. The powder coating page covers the callout in more depth.

Anodize on aluminum: Type II and Type III, clear and dyed, with a growth figure

Anodize is written as a type, a class and a color: "Anodize Type II Class 2 black per MIL-A-8625" or "Type III clear". Under that specification Class 1 means non-dyed and Class 2 means the coating is dyed after anodizing and before sealing (source 2). Source 1 gives Type II as coatings of 1.8 μm to 25 μm (0.00007 in to 0.001 in), says hard anodizing (Type III) can be made between 13 and 150 μm (0.0005 in to 0.006 in), and states that in commercial processes the oxide "is grown down into the surface and out from the surface by equal amounts", so a part grows by roughly half the coating thickness per surface. Type II takes dye and is the cosmetic and light-wear finish; Type III is the hard coat for wear faces (source 1). Dye shades vary with the base alloy (source 1), so the print names the color.

The number that matters on a print is the growth. The Aluminum Anodizers Council’s rule of thumb is 2/3 into the surface and 1/3 out for Type II, and half in, half out for hardcoat (source 14), so a Type II coat at its thickest, 0.001 in, grows each surface by about 0.0003 in. Clear is Class 1 and dyed colors such as black are Class 2, on 5052-H32 and 6061-T6 blanks alike. Welding is harder through an anodic layer, because the oxide is an insulator with a much higher melting point than the aluminum under it (source 1), so a part that needs welding is welded first and anodized last. For a reamed hole or a slip-fit pin bore on a laser-cut 6061 plate, the print either tolerances the hole after coating or masks it, and the quote flags any hole that cannot hold its tolerance as drawn. Anodizing on laser-cut aluminum, powder coating and passivation are quoted with the cut parts. Finishing a laser-cut part you already have is not quoted. Grade detail is on the aluminum spoke, callout detail on the anodizing page.

Steel and stainless: powder coat and passivation

Mild steel needs something against rust, and on a laser-cut steel part that is usually powder coat, written with a RAL number, gloss and texture as above. A finish called out on the print is quoted with the part. A coating does not replace edge preparation, so a deburr callout still belongs on the print.

Stainless gets passivation, not plating. ASTM A967/A967M-25 (source 9), the Standard Specification for Chemical Passivation Treatments for Stainless Steel Parts, covers immersion in nitric acid, immersion in citric acid and electrochemical treatment, and lists the water immersion, high humidity, salt spray and copper sulfate tests among those a lot may be checked by. Its scope says the tests are qualitative tests intended to confirm the effectiveness of passivation, particularly the removal of contaminant iron and other exogenous matter. Write "Passivate per ASTM A967, citric" or "nitric" on 304, 304L, 316 or 316L parts; those acids remove surface iron and rust while sparing the chromium (source 10). A cosmetic requirement on a stainless face, such as discoloration at a cut edge, goes on the print as its own note. See the passivation page and the finish hub.

Order of operations: cut, form, machine, weld, then finish and hardware

The finish follows the cutting, forming, machining and welding, and the print sets where hardware falls. PEM’s installation guide says not to install steel or stainless steel fasteners in aluminum panels before anodizing or finishing, and not to install a fastener on the pre-painted side of a panel (source 11), so an anodized aluminum part is finished first and the hardware goes in after. PEM also lists thread masking plugs for the paint or powder coating process (source 12), which is the route when hardware goes in before coating and the threads stay clear. For powder-coated aluminum those two notes pull in opposite directions, so the order goes on the print. Hardware insertion covers the hole sizes and the PEM sources; here the point is that "install after finish" or "install before finish, plug threads" is a line the print should carry.

Machined features follow the same logic. A tapped hole, a reamed bore or a machined edge is drawn with its tolerance and the note "after finish" or "before finish", and the quote reads that note to decide masking. When a laser-cut steel part is also welded, all coating comes after the weld, and the print says what the weld area needs to look like, such as spatter removed or the bead ground flush. The welding spoke covers welded laser-cut assemblies. The ordering how-to is on laser-cut, tapped and machined as one order; the laser-cut parts hub lists every secondary operation that can ride on the same quote.

How the finish is inspected, and what to send

The finish is part of the inspection against your print: color against the RAL or named standard on the order, gloss and texture as written, masked areas bare, and any post-finish dimension the print gives. If a part doesn’t match the print, it’s remade or credited.

To get a finished laser-cut part quoted in 24-48 hours, send a DXF or STEP of the profile and a PDF print. Name the material and thickness on the print. Write the finish as a standard and a color (RAL number, anodize type and class, ASTM A967 method), add the gloss or texture, every masked feature, the hardware and machined-feature notes with "before" or "after" finish, and any face that must stay bare or as rolled. Ask for more than one quantity, such as 1, 25 and 100, and the quote shows each. With no drawing, a dimensioned sketch, a new sample part or photos are enough to start; the CAD work is then quoted as its own line, and the quote lists anything missing. A fully dimensioned 2D PDF is quoted without a CAD line. Any file type is accepted; those lines let a finish be quoted with the part instead of questioned. There is no minimum, and lead time is quoted per job with rush available, through the quote form.

Sources

All accessed 4 October 2026. Where a figure here differs from your print, the print governs.

1. Wikipedia, "Anodizing": en.wikipedia.org/wiki/Anodizing (Type II coatings of 1.8 μm to 25 μm, 0.00007 in to 0.001 in; hard anodizing can be made between 13 and 150 μm, 0.0005 in to 0.006 in; oxide grown down into the surface and out from the surface by equal amounts, so each surface grows by half the oxide thickness; the oxide is an insulator with a much higher melting point than aluminum, which can make welding more difficult; dye colors vary with the base alloy).

2. Products Finishing, Larry Chesterfield, "What is the Correct Anodizing Specification?", 1 May 2010: pfonline.com/articles/what-is-the-correct-anodizing-specification (under MIL-A-8625, Class 1 means non-dyed and Class 2 means dyed after anodizing and before sealing).

3. Wikipedia, "Powder coating": en.wikipedia.org/wiki/Powder_coating (typically applied electrostatically and then cured under heat or ultraviolet light; can produce thicker coatings than conventional liquid coatings without running or sagging; thin films tend toward an orange-peel texture).

4. Wikipedia, "List of RAL colours": en.wikipedia.org/wiki/List_of_RAL_colours (RAL 9003 signal white, RAL 5010 gentian blue, RAL 7040 window grey), and "RAL colour standard": en.wikipedia.org/wiki/RAL_colour_standard (RAL Classic colours moved to a four-digit system).

5. Wikipedia, "Rust": en.wikipedia.org/wiki/Rust (iron in contact with water and oxygen rusts; rust prevention requires coatings that preclude rust formation).

6. finishing.com, reader thread "Powder Coating Shrinkage on Edges", 2002 with replies to 2016: finishing.com/165/65.shtml (an answer that the residual material left by the laser must be removed before topcoating; an answer to round the sharp edge before powder coating; "Powdercoating and most coatings is thinnest at the edges"). Reader answers, not a standard.

7. Products Finishing, "Chipping Edges", Ron Jacob, Finishing Help, LLC, 1 September 2006: pfonline.com/articles/chipping-edges (a very thin hard oxide forms on a laser-cut steel edge; typical pretreatment cleaners do not normally remove it; the fix is oxide removal by mechanical or chemical means). Plain text because the byline names the author’s company.

8. ARKU, "Why you need a deburring machine after laser cutting": arku.com/en/blog/why-you-need-a-deburring-machine-after-laser-cutting (burrs are pointed, sharp-edged residue; aluminum tends to create more burrs than other materials; material can solidify below the kerf if it cools too quickly). Undated. Plain text because the publisher sells deburring machines.

9. ASTM International, A967/A967M-25, "Standard Specification for Chemical Passivation Treatments for Stainless Steel Parts": store.astm.org/a0967_a0967m-25.html (Active, last updated 24 January 2025; nitric acid, citric acid and electrochemical treatments; water immersion, high humidity, salt spray, copper sulfate and other tests; the tests are qualitative tests intended to confirm the effectiveness of passivation, particularly the removal of contaminant iron and other exogenous matter). Referenced, not reproduced.

10. Wikipedia, "Passivation (chemistry)": en.wikipedia.org/wiki/Passivation_(chemistry) (nitric and citric acid baths remove surface iron and rust while sparing the chromium; some grades resist rouging and may forgo passivation depending on engineering decisions).

11. PennEngineering, "Self Clinching Nut Fastener Installation Do’s And Don’ts": pemnet.com/products/engineering-guides/self-clinching-fastener-installation-dos-and-donts/ ("Don’t install steel or stainless steel fasteners in aluminum panels before anodizing or finishing"; "Don’t install fastener on the pre-painted side of the panel"). Undated. Plain text because the publisher sells fasteners.

12. PennEngineering, "CL Self-Clinching Nuts" bulletin: pemnet.com/wp-content/uploads/sites/2/2022/06/cldata.pdf (PreTect thread masking plugs for improved thread protection during the paint or powder coating process; the suffix TP orders a fastener with a pre-installed plug). Marked © 2026 PennEngineering. Plain text because the publisher sells fasteners.

13. Products Finishing, Rodger Talbert, "Proper Coating Thickness", 1 November 2013: pfonline.com/articles/proper-coating-thickness (typical film thickness around 2 to 3 mils; each powder’s range is on its technical data sheet; byline names no employer).

14. Aluminum Anodizers Council, "A Conclusive FAQ Guide for Anodized Aluminum": anodizing.org/anodized-aluminum-faq/, no date shown (under nominal Type II conditions the rule of thumb is 2/3 in, 1/3 out; under hard coat, Type III, half in, half out).