The product you are using is not really a wood finishing product. It's primarily a fungicide designed to, well, preserve wood - things like joists and floorboards. It doesn't repel water. I honestly would not use it for an interior project like a desk particularly if you're eating off of it.

You need to use a proper top finishing coat like a compatible oil based polyurethane. Sand down to 220 or so like the previous comment and use a few coats of poly sanding lightly with 320 or higher grit in between.