WEEK COMMENCING 10 SEPTEMBER 2023
It’s been a real struggle keeping up with everything lately. If you’re one of our readers who likes to download the pdf of the Newsletter, my apologies to you. It’s one of the jobs I usually do first thing on Friday morning after the Newsletter has been sent out, but time has just run away with me lately and it hasn’t been done. I will catch up on all of them today, hopefully.
Well, it’s been hot recently, hasn’t it? I know that I’ve been out and about giving a few demos, and they always seem to fall on the really hot days. Which means I’ve had to change my demo accordingly because of the heat, and I had a question come in this week wondering about the effect of the temperature on finishes, and particularly waxes.
So, I thought I’d do a little feature about how our finished react to the extremes of weather we have had recently…
As I mentioned above, I’ve had to change the order in which I normally do my demos; this is because when most club demos start it’s still been very hot, which can play havoc with finishes. Like most liquids, sealers, lacquers, and polishes become less viscose/more fluid when they get hot. I can just about remember something from my schooldays about the molecules being able to spread out more, making the liquid runnier. This means that it will be very easy to dispense more than intended, which can lead to putting too much of the product onto the timber. I always say that thin coats of product always give the best results when finishing, so this could be a problem. Thinner products also dry quicker, and combining this with a warm environment will also lead to difficulties. Many of our finishes are quick drying to begin with; add these factors into the equation, and it can become almost impossible to get an even coating onto the wood.
Friction Polish can be especially susceptible to this, as it can dry on the surface of the wood before it has chance to buff up whilst the lathe is running.
Obviously, waxes melt when they get hot—think of a candle. Paste waxes have a solvent in them to make the wax softer, which means they will melt even quicker and can turn to liquid. You’ll know if this has happened when you pick a tin up—you’ll hear it sloshing around inside.
This doesn’t mean it’s curtains for the wax; leave the lid on—because if you open it and spill it, it’s a nightmare to get spilt wax off of anything! — and put it in a cool place to set. Keeping the lid on also stops the solvent from escaping, and once the wax has cooled down it will return to its normal state.
If it’s a wax like Cut’n’Polish, you can carefully remove the lid and give it a gentle stir, to make sure the abrasive is distributed evenly. This isn’t normally required, though, as it’s very light and unlikely to sink to the bottom of the can.
If you’ve been fortunate enough (or maybe unfortunate?!) to attend one of my demos, you’ll know that I say how important it is not to touch the surface of the bare wood with your hand. This is because any natural greases and oils on your fingers could be transferred onto the wood, and this can cause problems for a coating to properly adhere to it. This will usually show up as white ‘fingerprints’ in the finish, a sure sign of poor adhesion.
If you do find yourself having an issue with this (let’s say someone else handled the wood before you got to it), the best solution is to wipe the surface down with surgical spirit. It’s great at removing the oils you don’t want to be there.
One last point to consider about the accelerated drying times of some of the products, mostly the aerosols. In hot weather, the spray will dry quicker. This could mean that it’s dry before it reaches the intended surface, and if this happens, it probably won’t stick to the surface properly. It might hold on, somehow, but even a light contact could cause it to just brush away like dust. Even if it does manage to adhere, it might not flow out as it should, leading to a surface that’s rough to the touch. If you must spray on a hot day, hold the can just a bit closer than normal, taking care not to flood the surface.
As a general rule of thumb, I always say that if the workshop is a comfortable temperature for you to work in, your finishes will be happy too. If not, do what I do at demos, and wait until it has cooled down a bit before using them.
I’ll see you again next week, have fun till then