Two neat cuts meet in the corner, almost. The small triangular gap waits for someone to call it a painting problem. It usually deserved a little more attention before the paint arrived.
Understand what the two joints are doing
The Home Depot's baseboard guide shows coping an inside corner by fitting a shaped end to the adjacent profile. A plain square board and a detailed moulding do not present the same joint. Outside corners require their own treatment.
Judge a sample in the actual corner
Ask the carpenter to dry-fit offcuts of the chosen material where the walls meet. Look at the top edge and profile alignment as well as the seam. Paint-grade and clear-finished trim allow different finishing options, but neither benefits from an unnecessarily large gap. Seasonal movement also makes a promise of permanently invisible joints unrealistic.
Before the next step
- Choose the actual profile and material before agreeing on the joint.
- Review a dry-fit sample in an imperfect corner.
- Keep finishing expectations appropriate to paint or clear finish.
A tidy corner is a small pleasure that repeats around the room. It is worth fitting the pieces to each other before asking filler to introduce them.