Speeding up the drying process

[Patrick Galpin]

I visited a wood floor company the other day and they often stain the wood floor pieces, then pass them through a drying unit that looked like UV lites. The same process was used when they applied two coats of tung oil. Can anybody comment on the effectiveness or problems this might cause?

[Scott Holmes]

UV to cure tung oil... hog wash. I would be very suspect of any company that's claiming to use tung oil as a finish on a floor. It is a very poor finish. Now, Varnish made from tung oil would be a different story.

They could be heat lamps which could speed the process a bit. I'm guessing it "could" also be some high tech UV cured finish; it's not tung oil.

[Harvey Pascoe]

I use the sun on my varnished products (UV and heat) cuts drying time by two thirds.

Problems can arise depending on what you use as an undercoat. Shellac under varnish, if not fully cured, will continue to gasify and result in blisters due to the heat. So be sure any undercoat is fully cured before using heat.

[Bob Wingard]

I use the sun on my varnished products (UV and heat) cuts drying time by two thirds.

I think one day that technique is going to bite you right on the butt ... I have a friend who built a beautiful coffee table as a gift ... he was running short on time ... applied a couple of coats of finish ... set it out in the sun to "cure" ... came back a few hours later, and the finish was as smooth as 60 grit sandpaper ... we suspect the finish acted somewhat like a magnifying glass and intensified the UV to the point that most of the visible surfaces blistered so badly, the whole piece needed to be stripped and done over.

I vowed I would NEVER try to rush a finish to meet a schedule ... hence the phrase "I love deadlines ... especially the WHOOSHING sound they make as they go by"

[Scott Holmes]

Bob,

LOL "I love deadlines ... especially the WHOOSHING sound they make as they go by"

[Patrick Galpin]

Scott, I should have mentioned that the tung oil was applied over stain and then had two coats of a satin varathane finish applied.

[Chris Fournier]

UV curing on prefinished flooring is standard industry practice. Tung oil and then varathane is not.

[Harvey Pascoe]

I think one day that technique is going to bite you right on the butt ... I have a friend who built a beautiful coffee table as a gift ... he was running short on time ... applied a couple of coats of finish ... set it out in the sun to "cure" ... came back a few hours later, and the finish was as smooth as 60 grit sandpaper ... we suspect the finish acted somewhat like a magnifying glass and intensified the UV to the point that most of the visible surfaces blistered so badly, the whole piece needed to be stripped and done over.


I've been doing this for seven years and no teeth marks on my backside yet. The blistering was probably caused by whatever was used as a stain or filler not being fully cured.

You don't put the part out in the sun and then walk away from it for "a few hours", that was another mistake. I am in Florida and the sun is intense and I have to regulate the heat build up. Varnish on white wood is one thing, on dark wood a whole 'nuther matter. I regulate the heat build up by using a piece of window screen in a frame to filter the sun and check the temp with an infrared thermometer. Poly varnishes dry as fast as 45 minutes and alkyd or spar about two hours, so the later needs some kind of heat control.

If I am using a grain filler, I cure that in the sun also. I need to be sure that it isn't going to create gas with heat and cause blistering.

[Bob Wingard]

The blistering was probably caused by whatever was used as a stain or filler not being fully cured.

UHHH ... probably NOT ... there was no use of stain OR filler !!! It was a wiping varnish applied directly to QSWO. The finish had already been allowed to dry for a few days before he set it out in the sunlight.