Get a more accommodating brand of paint and have it color matched to what you want.

Okay…so no concern that the sheens won’t match up?

Overthinking, I’m sure, but this area gets a lot of sun so I want to try to make it as close as possible

Need same brand, same type paint and same sheen, I believe, or you may need to repaint it all. But it all depends on how fussy you are.

I believe that the sample sizes do not have the proper binders in them to behave like actual paint.

I would buy a can of the exact same paint you used, so you do not have to worry about the difference in sheens in other brands. It keeps a long while, if you keep it in a clean cool (not cold), dry place. You will most likely need it again in the future.

I can logic through how one brands "eggshell" sheen my not be the same as another's but flat seems like it would be flat. Do they have any samples? They aren't cheap but you could paint a piece of wall board and see how it matches? Most companies sell quarts which also would be cheaper. Put frankly I would color match from another brand and move up from flat. Even one sheen up. Flat is near impossible to clean/keep looking decent.

I totally agree with you that flat is nearly impossible to keep clean, and still don’t understand why they would use it in a high traffic area like a hallway, foyer and stairwell (especially knowing young children live here). I’m assuming you mean switch sheens the next time we repaint, correct? Thanks for the suggestion and you make a good point. 👍🏻

I have no idea why SW can’t mix this in a quart size for you! It may depend on what grade paint the painters used! Do not try to get it color matched from a different paint company. A different sheen will be very obvious as well and you will need to repaint the entire wall. Using flat has its advantages for just this type situation; one can touch up without having it “flash” and having to repaint the whole wall! If you are concerned about washability you may have considered going to a matte finish instead. As the matte finish only is available in the higher priced products it would be an upgrade for some. I am a bit surprised your painter did not leave some of the original paint just for this very reason!