How to varnish a Hevia timber benchtop?

Macrozzie

Can anyone help please?  I bought a hevia timber benchtop, gave it a sand with 240 grit sandpaper, then used a Cabot's oil-based varnish in gloss to coat it.  When dry, the surface feels really rough and prickly.  I don't have much experience but I have varnished a solid bamboo benchtop I got from Bunnings a few years back, and it looked really good after the first coat, but the Hevia benchtop is obviously very different.  I was hoping someone would know if I need to remove the oil-based coating, or if that's even possible and start again and what to do without ruining the benchtop?  If anyone has had any similar experiences, I'd be grateful for any advice. TIA

JacobZ

Hi @Macrozzie,

Welcome to the Bunnings Workshop community, it is fantastic to have you with us.

Hevea timber, also known as rubberwood, behaves quite differently from bamboo, which is why your benchtop finish has turned out rough after the first coat. Unlike bamboo, which is dense and smooth, Hevea has a more open grain and porous structure. When you applied the varnish, the wood fibres absorbed it unevenly, causing them to swell and stiffen. This raised grain is what makes the surface feel prickly to the touch. It’s a common reaction for many hardwoods after the first coat of varnish, so you haven’t done anything wrong.

The good news is that you don’t need to strip the varnish or start again. All that’s required is to sand the surface lightly to smooth down the raised fibres. Once that’s done, each additional coat of varnish will build up a smoother, more durable finish.

To fix the problem, wait until the varnish has fully cured, which usually takes at least 24 hours, and may take longer in cooler or humid conditions. Then, lightly sand the surface with a fine-grit sandpaper, like this Flexovit 100mm x 1m 400 Grit Sandpaper. The aim here is not to remove the varnish, but simply to knock down the roughness. 

After sanding, wipe away all the dust with a clean cloth to ensure the next coat adheres well.

You can then apply another thin coat of varnish, brushing with the grain. As you repeat this process — light sand, wipe clean, recoat — the surface will become progressively smoother. Typically, three to four coats are needed for a benchtop to get both a durable protective layer and a nice finish. 

Let me know what you think and if you have further questions, please don't hesitate to ask.

Jacob