Help needed repairing benchtop.

[cjbfisher]

I have some benchtops at work that were ready to go out and be fitted, and yesterday while I was out a chinese fella damaged one of them. I wouldn't normally have anything to do with this, but the boss is away until the day after they are due to be installed, so I have to repair it myself. The tops are laminated Melunak and have previously had 2 x coats of Feast Watson sanding sealer, followed by 2 coats of oil based Cabothane in a satin finish.
Yesterday I sanded back with 240 grit, and in some places I got down to bare timber. I really want to sand again with 320 or 400 because the original prep was pretty bad, but I'm conscious of time (needs to be installed on Wednesday) and dollars (it's meant to be a budget job). Really, I feel that I should take it all back to bare timber and start again, but I just can't.
In places I can see a sort of mottling effect. I assume this is where I have sanded right through the Cabothane back to the sanding sealer.
What is the best way for me to tackle this?

[FenceFurniture]

Ring the Boss.

The usual mantra with polyurethane is that it can't successfully be patched properly.

[cjbfisher]

The usual mantra with polyurethane is that it can't successfully be patched properly.

I really didn't want to hear that.
So it's basically, take it back to bare timber and start again?

[FenceFurniture]

Yeah, sorry about that. Wait for some other opinions first.

[Kuffy]

I would respray the entire problem benchtop. Starting off by hand sanding in the direction of the grain with 240grit to give the surface some tooth to adhere to. Then spray as many coats as needed to make the problem top look the same as the others. I have never worked with Melanuk before so I have no idea how coarse the grain is, but I would expect to need to spray at least 3 coats. You won't see the witness lines that will have been created between the raw wood -> sealer -> cured poly areas under three coats of fresh satin poly.

[cjbfisher]

Thanks guys. I’ve bitten the bullet. Right back to bare timber. Going to have to do both tops though to make sure they look the same.