Add a waterproof finish on top of lacquer

[David_DIY_idiot]

My partner bought a sideboard she wanted me to upcycle. I painted it with furniture paint and given it a few coats of chalky finish spray lacquer but she's since decided she'd like to convert it to an undersink unit with countertop basin.

Is there a finish I can apply directly on top of the lacquer that will make it waterproof(ish) and be able to withstand mild cleaning products without having to sand it back?

Does clear varnish play nice on top of lacquer? I've googled but got some conflicting reports so thought I'd see if anyone has any experience/thoughts.

Thanks in advance.

 

[foxhole]

Two part varnish is very hard wearing .
https://www.amazon.co.uk/Sadolin-Li...ocphy=9044972&hvtargid=pla-698500010059&psc=1

 

[Deleted member 174758]

You may find that trying to put a clear lacquer on top of a gloss coat won't work that well and can peel off, especially if the materials are incompatible. I'd be thinking in terms of reducing the gloss to a matt finish somehow (to gain a mechanical key) and possibly of adding a inter coat coat of shellac (white dewaxed French polish) between the layers, but I suspect that @opps, who is a trade deco, is probably your man to answer this one

 

[opps]

TBh, without knowing which lacquer you used it is hard to say. Conventionally, lacquers are shellac based and pretty resistant to most cleaning products but will be dissolved by the likes of meths and ammonia. The term lacquer has however become misappropriated over the years.

I used to danish oil my worktops but became fed up with having to re-oil them all the time. I sanded them back and used a 2 part acid catalyst and sprayed them, but the stuff should not be sprayed without a clean air supply.

Off hand I don't think that "varnish" over a shellac based varnish will cause any problems but you would need to key the lacquer with a minimum of 240 grit paper. That said, I am not convinced that varnish is the best option. Again, what does varnish even mean these days?

I think Foxholes's suggestion (an epoxy "varnish") might be a good choice. It will definitely be more scratch resistant. Acid cat paints are considered to be "hot paints", by that I mean that they might melt the existing finishes.

Another alternative might be a polyurethane lacquer such as this (pub bar grade), but they recommend sanding back to the wood...

Other than the supplier in the link above, another supplier that I have always found to be very helpful is Smith and Rodgers in Glasgow

https://www.frenchpolishes.com/index.htm

An other alternative is a sheet of toughened glass (polished corners, edges) with a cut out for the basin. It will be the most resilient finish.