Burning through a finish while buffing

[Glen Blanchard]

How does one know he/she has burned right through the finish and are down on bare wood? I've heard this discussed many times but don't know that I would know if it happened to me as I don't know what to look for.

[Scott Hackler]

Glen,

If your buffing a top coat (poly or lacquer) overheating caused by too much pressure or too fast on the wheels, can melt the finish and you'll see it pretty easily. You can't really buff through an oil finish as it's soaked in, but the chance of burnishing will still make you take it easy with the buffing. Techniques vary, but I buff at 600rpm (ish) and keep the piece moving with just enough pressure to know the wheel is in contact.

[Glen Blanchard]

Thanks Scott. I was referring primarily to a lacquer finish. I typically apply 6 coats by brush (thinned 50/50 with lacquer thinner) and then buff after the lacquer (presumably) has cured. It sounds like if I have never noticed a problem develop while buffing that I probably have never burned through the lacquer.

[robert baccus]

Glen, buffing through is the big gorilla in buffing anything. If you do it will show i promise. You might try wet sanding with 220-400 sponges just lightly before buffing. Much faster and reduces the temptation to buff harder or faster. Watch for the shiney laq. orangepeel vrs. flatter sanded areas and stop at 80% sanded and go to buffing. As you are brushing try a light misting of rattlecan laq. retarder before sanding--it will lay down orangepeel or brushing marks. Also there are liquid auto buffing compounds which make burning almost difficult, applied by rag while turning or buffing wheel. I only use a wheel on small handheld items.

[Prashun Patel]

Lacquer and shellac don't form layers; they fuse into a single layer. So, if you burn through - which will manifest as dull spots, then just apply another layer of finish.

An oil finish or oil/varnish finish doesn't build any layers; they stay in the wood, so burning through is not an issue with these.

A varnish finish (like poly) forms distinct layers. Burning through here manifests as areas that look like the finish has peeled away. The fix here is to sand the ridge as smoothly as possible, then apply several more layers, under which the burn through should become less visible (not necessarily invisible).

If yr buffing with compound or wax; you'll need to remove that as much as possible before applying any additional finish.