[rdrimmie]

The knowledgable folk will probably benefit from knowing your region and if there is anything regarding IP in your employment contract.

Anecdotally, my employment contract has a clause that grants my employer shared copyright to all my work unless they officially disclaim interest, but because that clause exists there's also a pretty simple process: I present a 1-paragraph overview of the project and someone with signatory authority writes on the paper "[My employer] is not interested in this project." Then signs it.

I don't know how well this would stand up if it ever came down to a court case, and there's definite benefit in that there's only 8 of us here so pinning down such an authority is a matter of me putting the paper on the desk next to mine.