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A Cosmetic Standard You Can Attach to a Purchase Order
Machining tolerances are numbers, so they are easy to agree. Surface quality is a judgement, which is where nearly every dispute in this niche ends up. One page, signed before anyone cuts metal, prevents almost all of it.
Asking for a flawless finish is not demanding, it is unpriceable. There is no inspection method for flawless, so a careful shop pads the quote and a careless one agrees and argues later.
COSMETIC STANDARD - <PROJECT NAME>
Revision 1, <date>. Attached to and forming part of purchase order <number>.
1. VIEWING CONDITIONS
Parts are inspected at 400 mm, under diffuse lighting of approximately
500 lux, for 10 seconds per surface. Defects visible only outside these
conditions are not grounds for rejection.
2. ZONES
Zone A, primary : top surface, front face, both side faces.
Zone B, secondary : underside, rear face, area around the port cutout.
Zone C, hidden : internal pockets, gasket shelves, plate underside,
any surface not visible on an assembled board.
Zones are marked on drawing <number>, sheet <n>.
3. LIMITS BY ZONE
Defect Zone A Zone B Zone C
Scratch / witness mark none visible max 3 mm, no limit
max 2 per face
Blast texture variation none slight, even no limit
Racking mark not permitted permitted, permitted
underside only
Dent or ding none none no limit
Burr none none none
Contamination none none none
4. COLOUR
Colour is judged against the approved golden sample, not against the
drawing note, the reference number or any render. Both parties hold a
copy of the approved sample, dated and signed on <date>.
Reference used for the initial brief: <Pantone / RAL>.
5. BATCHING
All parts that meet in a visible seam, including the top case and the
bottom case, shall be processed in the SAME anodising load.
6. OVERAGE
Expected cosmetic scrap rate: <n> percent, agreed at quotation.
Blanks started: <ordered quantity + overage>.
Cost of overage is carried by <buyer / supplier>.
Good parts above the ordered quantity are <shipped / retained / scrapped>.
7. BORDERLINE BATCHES
Where a batch is outside this standard, the remedies are, in order:
a) strip and reprocess, where the part can take it;
b) accept with an agreed price adjustment;
c) remake from raw stock.
The choice is the buyer's. Supplier to notify within 2 working days of
discovery rather than at shipment.
8. PRECEDENCE
Where this document and the drawing disagree on surface quality, this
document governs. Where this document and the approved golden sample
disagree on colour or texture, the sample governs.
Signed for the buyer: ____________________ Date: __________
Signed for the supplier: __________________ Date: __________This is a plain commercial document, not legal advice. Have your own terms reviewed if the run is large enough to matter.
The four clauses that do the work
The rest is useful. These four are the ones that decide whether a disagreement takes ten minutes or six weeks.
- Viewing conditionsDistance, lighting and duration, as numbers. It excludes defects only visible at 100 mm under a raking spotlight, which is fair, because that is not how a keyboard is used.
- ZonesThe single most effective cost control on the page. A shop that knows zone C is hidden will not slow a finishing pass for it, and that is real money on every part.
- The golden sample governs colourWords describe colour badly and renders describe it worse. One approved physical part ends the argument because both sides are holding the same object.
- Borderline remedies, agreed in advanceStrip and reprocess, accept with an adjustment, or remake. Naming the three options before one is needed turns a crisis into a decision.
Where the limits come from
The reasoning behind each clause is in writing a cosmetic standard, and the process behind the colour clause is in how anodised colour is really decided.