The samples are on the table in the studio and the client is in another city. You need them to pick a cladding, a window spec, or a roof finish before the order window closes. Your assistant drafted a generous email with three manufacturer names and a paragraph of weather talk. The client replied "looks good" and you still do not know which one they chose.
A material choice is a decision with a later cost. Once it is ordered, the other options are gone. The message has to make that visible without turning into a lecture.
Close the list and say what each option spends
Two or three options, written as if you had no favourite. For each: what it is, what it does to the programme, and what it rules out once the order goes in. Then your recommendation, in its own paragraph, and the fact that would change your mind — a lead time you have not confirmed, a sample they have not seen in daylight.
Asking for a decision is the general shape. The architect-specific part is that "the warmer one" is not an option. Name the product and the finish. If two samples look alike in a photograph, say so, and say which difference only shows on site.
Do not bury the choice under the history of how the design got here. They already hired you for that. They are being asked to live with a surface.
Put the premise that would change the pick on its own line
Most material regrets start as an unstated premise. You assumed the elevation gets afternoon sun. You assumed they still want the dark mortar. You assumed the contractor can source the second option in time. Write each assumption as a sentence someone can answer no to.
Clients correct a labelled line. They do not correct a paragraph that already sounds decided. If your assistant inferred that they prefer the cheaper face because they once mentioned budget, mark that as inferred. Fluency is not a site visit.
This is not the mid-renovation ambush, where a wall is already open. This is a planned choice. You have time to write it. Use the time on the options, not on a reconstruction of the last meeting.
Describe the sheet; do not send the packet
RelayLink does not carry attachments. A briefing that says "see the PDF" has no decision in it. Describe the document: who published it, the product code, the one performance claim you are relying on, the colour name as the manufacturer prints it. If they need the sheet, they already have it, or you send it on the channel you already use for files.
You approve the send. The note they read should be in words they would recognise as yours, not a studio nickname they have never heard. A nickname you keep for them stays on your side of the contact list.
They do not need an account. If they are not on RelayLink, the ask travels as email and a link. If they already have an activated account, you need an accepted pair for a new thread. They can reply from the mail. That reply is the record of which face went on the building.
When to get on a call
If the samples only make sense in the hand, say that and book the look. Writing cannot replace daylight. Writing can still pin the choice after they have seen it: which option, which reservation, which date the order must leave.
Send the closed list. Wait for the named option. Do not accept "looks good" as a specification.