The short answer
Bead blast and tumble/vibratory finishes both cosmetic-clean CNC parts, but they package differently on an RFQ. Blast is line-of-sight and mask-friendly; tumble is bulk and edge-rounding. Say which—and where—so [quote-new.php](https://3dwk.com/quote-new.php) **rates.v1.1** estimate adders stay in band instead of **needs_manual**.
This guide is for buyers writing finish blocks. Illustrations are **Example part** only. Process comparison background: [bead blasting vs tumbling vs vibratory finishing](https://3dwk.com/resources/bead-blast-vs-tumble-vs-vibratory-finish); here we focus on **RFQ packaging for preliminary estimates**.
Bead blast packaging notes
Call media family (glass / ceramic / stainless), target Ra if it matters, and faces that must stay unblasted (seals, datums, bearing bores). Mask maps belong on the PDF. Blast after machining and before or after anodize—sequence changes color and growth stories. Related: [surface roughness Ra](https://3dwk.com/resources/surface-roughness-ra-for-machined-parts), [how anodize choice changes CNC RFQ cost](https://3dwk.com/resources/how-anodize-choice-changes-cnc-rfq-cost), [edge break / chamfer / deburr](https://3dwk.com/resources/edge-break-chamfer-deburr-callouts-cnc).
Deep pockets and undercuts may not blast evenly—say whether shadowed walls can stay as-machined.
Tumble / vibratory packaging notes
Tumble and vibratory are bulk processes. They round edges, can peen small features, and are poor at selective masking. Call media type, whether sharp corners must be preserved, and max part size/qty per lot. Threads and small holes may need plugs—state that.
Do not write “blast or tumble, dealer choice” if cosmetics or edges are functional. Related: [DFM checklist](https://3dwk.com/resources/dfm-checklist-before-online-cnc-quote), [what files to send](https://3dwk.com/resources/what-files-to-send-for-cnc-quote).
Illustration 1 shows an **Example part** with blast-only cosmetic faces vs tumble-allowed edges.
Estimate impact under rates.v1.1
Finish adders sit on top of machine-time. Soft materials (PA66 coeff ×0.8 under **rates.v1.1** estimates) can pick up media and show different cosmetics than 6061. Hot alloys (17-4PH ×1.4, IN718/IN625 ×2.5, CoCr ×2.2) may need different media or hand finish—ambiguous “cosmetic blast somehow” on IN718 often **needs_manual**, especially when the line mid exceeds configured USD thresholds.
Bar $/kg planning bands (estimates): PA66 ~5, 17-4PH ~9, IN718 ~55, IN625 ~60. Finish choice rarely changes bar cost; it changes handling minutes and risk.
Mixing finishes and inspection
Common pattern: tumble deburr → selective bead blast → anodize/chem film. Write the sequence. If FAIR needs Ra on blasted faces, say sample size. “100% visual class A all over” after tumble on a complex housing widens the mid. Related: [first article inspection](https://3dwk.com/resources/first-article-inspection-reports), [reading preliminary quotes](https://3dwk.com/resources/reading-preliminary-online-quote-min-mid-max).
Example part walkthrough
**Example part:** 6061-T6 bracket ~80×50×15 mm. Exterior cosmetic faces: glass bead, mask 2× Ø6 H7 bores and sealing pad. Edges: light tumble OK before blast, or hand deburr if tumble forbidden. Type II after blast. PDF shows mask map + sequence. Expect a clearer planning band on [quote-new.php](https://3dwk.com/quote-new.php) than “make it look nice.” **rates.v1.1** estimates only—Example part, not a customer cosmetics standard.
Illustration 2 contrasts a vague cosmetic note versus a finish-block RFQ with blast vs tumble decision.
What widens bands
Unspecified media, blast+tumble on the same faces without order, mandatory class-A cosmetics on tumbled threads, and hot-alloy blast without media guidance. Quantity helps unit cost but does not erase mask labor—see [quantity breaks](https://3dwk.com/resources/how-quantity-breaks-change-cnc-unit-cost).
Masking labor and fixture notes
Selective bead blast on a complex housing can cost more in tape/fixtures than the blast minutes. If only two faces are cosmetic, say so—do not imply full-envelope class A. Tumble avoids mask labor but may destroy intentional sharp edges and small embossed marks. Call out laser-mark keep-outs before tumble.
For anodized aluminum, blast before Type II is common for uniform matte; blast after dye risks color shift—state the sequence. Chem film under paint may want different cosmetics than Type III hardcoat wear faces—see [hard anodize vs electroless nickel](https://3dwk.com/resources/hard-anodize-vs-electroless-nickel-wear) when wear and cosmetics collide.
Small parts, media lodging and cleanliness
Tiny cavities can trap tumble media; call flush/clean requirements for hydraulic or vacuum parts. Stainless blast media on aluminum can leave contamination if not controlled—name media family. Soft plastics (PA66) can embed media; tumble may be wrong for precision nylon fits even when **rates.v1.1** PA66 time coeff ×0.8 looks attractive.
Qty 1–5 often favor hand deburr + selective blast; qty 100 may favor vibratory. State the cosmetic acceptance photo or standard if you have one—without inventing a customer brand standard. Related: [zinc vs EN vs black oxide](https://3dwk.com/resources/zinc-plating-vs-electroless-nickel-vs-black-oxide) when steel cosmetics enter the same RFQ package.
Steel and stainless specifics
Carbon steel tumble before zinc or black oxide needs different cleanliness notes than aluminum blast before anodize. Passivation after stainless blast is a separate callout—see [passivation vs electropolishing](https://3dwk.com/resources/passivation-vs-electropolishing-stainless). Do not copy an aluminum finish block onto 17-4PH without media and sequence edits; 17-4PH HT H900/H1025 (~+$60/lot estimate when configured) can sit before or after cosmetics—say which.
What to do next
Pick blast vs tumble (or sequence both), attach a mask sketch, upload on [quote-new.php](https://3dwk.com/quote-new.php). Services: [CNC machining](https://3dwk.com/cnc-machining-service.php), [materials](https://3dwk.com/materials.php). Treat **rates.v1.1** bands as estimates, not invoices. If **needs_manual** shows, answer finish questions rather than forcing a fake firm price.
Common questions
Can tumble replace bead blast for cosmetics?
Sometimes for uniform matte on robust parts. Not when selective faces or sharp edges must stay crisp.
Do I need Ra for every blasted face?
Only where function or customer cosmetic standards require it. Otherwise “glass bead, uniform matte, mask as shown” is enough for many planning bands.
Will bead blast fix tool marks in deep pockets?
Not reliably—line-of-sight limits apply. Call whether pocket floors may remain as-machined.
Does finish choice change material coeffs?
No. **rates.v1.1** machine-time coeffs stay with the alloy; finish is an adder story. Still label everything as estimates.