Poly required over Danish oil?

If the project is a baby changing table you need to use at least put a coat or two of poly on the top. That surface will - not "might" or "maybe" - will come into contact with urine, and urine is acidic.

Dave

Varnish will go over Danish oil though it does make the use of the Danish oil somewhat redundant.

Is it necessary? First and most important consideration when contemplating a finish is, does it provide the provide the protection needed for the piece. Considering it is a changing table I'd say yes.

Special considerations. Oak is an open pored wood so, to get a smooth surface finish I'd recommend a pore filler. One that dries clear. I'd also recommend, considering that varnish doesn't have a solvent, a complete and immediate cleaning of the gun immediately after spraying not to mention spraying it in the absence of anything you don't want to get coated with slow drying overspray and bounce back.

I wonder why you would put oil on first when you are dealing with oak. The only time I have put poly over danish oil was on a alder table. The clear danish oil added a very nice color to the alder, just what I wanted. Clear poly on alder can make the wood an unpleasant red.