US26D, 626, 630: A Finish Code Is Not a Colour

A buyer arrived in September carrying a competitor's part number, `rxfse25r510l32d3`. The manufacturer never resolved and it did not matter, because one fragment of it identified the buyer completely: 32D. That is not a colour name, it is a code in the North American finish system, and a purchaser who writes it is specifying to ANSI/BHMA. Our own catalogue answers in a different language — SSET, ACBK, CPBK — house codes that mean nothing outside our price list. This article is the translation, and the important half of it is where the translation stops.

Start with the part everybody already knows. US26D and 626 are two ways of writing the same appearance, satin chromium plated; the US number is the older convention and the three-digit number is ANSI/BHMA A156.18. Most cross-reference charts on the open web print exactly this, two columns wide, and stop. That chart is incomplete in the one way that costs a container.

A BHMA number encodes the base metal as well as the appearance. A156.18 designates the base in the code itself: steel, brass and bronze, and stainless steel are three different groups. So 626 is satin chromium plated on a brass or bronze base. 652 is satin chromium plated on a steel base. They are the same colour, they photograph identically, and they are not the same product — different corrosion resistance, different price, different service life. A specifier who writes 626 and receives 652 has been given a substitution, and on a public building that is a rejected submittal.

630 is the one that breaks the pattern, and it is also the most specified finish in North America. It is not a plating at all: 630 is satin stainless steel, solid, with the finish worked into the metal rather than applied on top of it. This is why 630 cannot be offered as an alternative to 626 on price. There is nothing to wear through, because there is no coating; and there is nothing to plate, because the part is already the metal the finish names.

The practical consequence is that a finish code alone cannot be mapped to a BHMA number. Our catalogue records a finish field and a separate material field, and the number only exists where both are known. CP on brass and CP on steel are two different BHMA numbers, and the finish field does not say which. So the mapping in our system takes both fields and returns nothing whenever either half is unknown or names more than one metal.

Run that across the catalogue and 77 of 519 published records gain a number — about fifteen per cent. The commonest are 630 and 629, satin and bright stainless, which is what you would expect from a catalogue whose largest material group is stainless steel; then 605 bright brass, 625 bright chrome, 626 satin chrome, 619 satin nickel. One record resolves to 652 rather than 626, and that single record is the whole argument of this article: same colour, steel base, different number.

The other 442 are worth listing, because a supplier who will not say why a field is empty is usually hiding a guess. On 277 records no finish is stated at all, which is a question for our factory and is on the list. On 20 the material field is empty. On 22 the material names more than one metal — "brass or stainless steel" is a choice the buyer has not made yet, so there is no base to designate. Eighteen are Antique Brass, which is a family of relieved finishes rather than one A156.18 number, and twelve say "stainless steel" without saying satin or polished, where 630 and 629 both fit and guessing picks one.

Fifty-six are zinc alloy, and that group deserves its own sentence because it is a fact about the part rather than a gap in our data. A156.18's base materials are steel, brass and bronze, and stainless. Zinc alloy is not among them, and neither is aluminium. A specification calling for 626 on a brass base cannot be met with a zinc-alloy casting however close the colour comes, and a buyer is better told that before a sample than after a submittal. Saying so costs us enquiries we would have lost anyway at the review stage.

So, in practice: if your specification is written in BHMA numbers, send us the number and the model you are cross-referencing, and we will answer with a number or with a dash and the reason. A dash costs you one question. A plausible number costs whoever installs it a rejected submittal, and it is the reason most finish charts on this industry's websites should be read as marketing rather than as specification.