I may be a scrooge but I believe that you should always use a coaster (or a napkin) on wood surfaces, especially when in someone else's home. It should become second nature, the force of habit. Because no one likes water rings on the coffee table. And because no one likes to be the nagging host who follows guests around surreptitiously slipping coasters under their glasses. Talk about a buzz kill.
Of course, many wood surfaces don't seem worthy of coasters. For example, a table that clearly isn't old or valuable and that appears to be coated in some kind of industrial-strength gloss impenetrable to water droplets. Still, it is wise to get into the habit of reaching for a coaster when placing your glass or mug on a wood surface (and other surfaces, for that matter).
Even if you are a like-minded coaster Fascist, what about your guests? How can you get others to stop putting their drinks down directly on your wood furniture? After all, coasters can be a drag. They can stick to your glass. They can be flimsy and unstable. And finding and using a coaster is a distraction, however momentary, from conversation and socializing.
Here are some suggestions.
• 1 Quantity. Buy a lot of coasters and put them everywhere.
• 2 Size. Buy coasters that are big enough to accommodate even the largest glass. You don't want your guest struggling to try to balance their glass on some flimsy little disk.
• 3 Materials. Choose cork or sandstone coasters (like in photos 2 and 5) that don't stick to the bottom of the glass. Sandstone absorbs the condensation from the glass, which is particularly likely when using ice. Cardboard disposable coasters are also very effective. They work in the bar with even the drunkest of clients — so they should last through your party.
• 4 Alternatives. If you don't like coasters cover your table with a runner or a smattering of hard table mats. I often use my set of silver-plated vintage mats that were designed for using under warm dinner plates but are great as oversized coasters (as in photo 4).
• 5 Go with slip-ons. Use slip-on coasters (like the lovely ones from ETSY in photo 3) so you know that wherever that guest may wander your furniture is safe. It is tempting to place a glass on top of a bookshelf, mantelpiece, dresser, newel post and other places you would probably not think to place a coaster at the ready.
How water-resistant is my furniture?
Even if you are on board with coaster use as a general principle, it is helpful to know what kind of furniture you have. Not only will it help you calibrate just how paranoid to be about water damage, but you will also know the best way to clean and repair any damage when it does occur. The kind of finish (the materials used to protect wood) a surface has determines its durability as well as which cleaning products to use. It is not always easy for the untrained eye to discern what kind of finish a given piece of furniture has. For example, my 19th century mahogany dining room table seems to have been finished with some kind of sealant. This means the piece is probably less authentic and therefore less valuable. But it also means it is much easier to clean and maintain. Water seems to roll off the surface but how can I be sure what prolonged exposure to a wet glass would do? Instead of risking doing damage, we use coasters.
I spoke to an antiques restorer in Australia (where I bought many of my antiques) and he said that any wood furniture that is super glossy and has an even sheen across the surface is probably finished with polyurethane, a lacquer, or some other kind of sealant. This means it is relatively water-resistant. But even these finishes may be damaged through prolonged exposure to liquids. So his advice has always been, "When in doubt, use a coaster."
Several websites provide tips for determining with certainty what sort of finish your wood furniture has — and what that means for routine maintenance and care. These techniques (many of which involve testing a part of the wood) are hardly appropriate at a party, of course, and should only be used on your own furniture!
The most vulnerable surfaces are those with a wax finish (many rare and old antiques; more common among antiques imported from the Old World). Oil-based finishes, common among vintage Danish modern pieces, are also high-risk for water damage.
Shellacs and varnishes can be moderately protective against water damage but the most durable finish (though not necessarily the most attractive) may be lacquer, which is very popular among American furniture restorers. Like polyurethane, lacquer is relatively durable and water-resistant.