Shellac versus polyurethane

IF you’ve just bought a piece of wooden furniture that is unfinished, like a book shelf or a picture frame, a coat of varnish will give it a pretty gloss, protect it against stains and make it easier to keep clean.

Shellac is a natural product made from lac bug secretions. It’s glossy and dries quickly so you can apply a coat in the morning, another in the evening and the next day it will be nice and dry.

The big drawback is that shellac doesn’t work well with water or heat, so the kitchen is not a good place for this. Also, this finish is affected by ammonia and alkaline household cleaners, so you have to check what products you use.

For something a bit tougher, a popular alternative is polyurethane. This is basically a liquid plastic that comes in all sorts of finishes from satin to high gloss.

The water- based ones tend to be sensitive but the oil- based ones are more hardwearing, so you can use them for the kitchen table where you might have warm plates and frequent spills. Polyurethane comes in pots and sprays so you can choose between a brush, roller or a can. Some are specially formulated so that you can rub them on with a cloth so that you’ve got a “handmade” look.

The main drawback is that this is a plastic so even application is important. Also, most take 24 hours to dry between coats, so you need to time things carefully if you want to apply several coats.

Finally, all finishes can potentially change the colour of the wood. This can be lovely for highlighting grain but be sure to read the instructions so you get what you need.

Or test a bit on a similar piece of junk before starting the big project.