An Experiment

[Jan]

Because there have been questions in my mind about finishing aspen so it stays as white as possible, I decided to do a little experiment. I masked a very white piece of aspen and sprayed one half of the board with Deft clear lacquer. When it was dry, I masked the finished area and wiped on Old Masters poly gel on the other half, making sure the finishes didn't overlap but were butted up together. When both finishes were dry, I took the board to someone who had no idea what the finishes were and asked if he could tell the difference. He couldn't. The only difference that was noticeable was that the wipe on poly surface looked and felt better. Neither had been sanded after application. Both sides of the board had picked up a yellowish cast and were essentially the same color. I was surprised because I had completely bought into the idea that the lacquer finish would not affect the color of the board.

Jan

[wood-n-things]

Good info to have. I have noticed though lacquer does yellow the wood depending upon species.

[Forester21]

Nice to know. Thanks for taking the time to do this and report on it. Where do you get the Old Masters?

[Jan]

Nice to know. Thanks for taking the time to do this and report on it. Where do you get the Old Masters?

I get the Old Masters from JGR. I haven't found a local source.

Jan

[paul44224]

Check myoldmasters.com They have a store locator tab. I have 4 locations within 10 miles of me. All "independant" paint/lumber supply stores. OM has a really excellant product line, and I like going to the locally-owned stores if at all possible.

[Wood Dog]

Thanks for the great link paul44224.

[Janette]

I was looking at liquid minwax poly finish in the store yesterday and was surprised to see that it is an oil based product. I had always thought it was water based. I'm sure there are more that are - and the selection at the local Walmart where I happen to be is extremely limited. I will look more next time I'm in somewhere like Home Depot where there is a greater selection. I use the spray for my magnets - I still have trouble getting it into the edges and usually end up putting too much on everywhere else just to get the nooks and crannies covered at all. I think it would probably be ok to do this with individual pieces prior to gluing but I have trouble doing it with a completed project. Probably just me! I have put gel varnish over water based in the past with no problems - I used the water based on the white areas to keep them white - then finished the entire project with gel varnish to give a consistent look. I'm trying to find something that will keep the whites whiter - and still get the same look as the gel - to make life easier.

[dedijerry]

Cool idea Jan you should post a pic and let us see! You should also try some others and send your results with some pics to Bob maybe he will put your info in the mag. Very good info to know for a lot of people.

[Jan]

If I use the spray, it's always before gluing the project together. It took some time before I got smart enough to put several light coats on anything I spray painted instead of loading the wood up with too much finish. Had some world class runs before I got that under control. I prefer the appearance of the poly gel finish, but have to admit that Deft with buffing between coats with a very fine grit sanding mop looks really good.

@ Paul: Thanks for the link to Old Masters. Unfortunately, the nearest supplier is about 35 miles from me. Considering the 70 mile round trip, I think I'll continue ordering from JGR. Her customer service is great and I'm sure the cost of postage is now less than the fuel used for the trip.

Jan

[Bill Wilson]

Hi Jan,

I think some of the confusion regarding lacquers is because there are several types of lacquer and their properties can be quite different. The most common lacquer, especially those found in spray cans, is nitrocellulose lacquer. It is popular with hobbiests because it is easy to apply and dries fast. However, it will tend to impart a slight amber tint and will yellow some with age. This will affect the appearance of light colored woods.

Acrylic lacquers are completely clear and will not impart any tint to light colored woods. Inbetween these to ends of the color spectrum are catalyzed lacquers, typically used by professional finishers, but also popular with serious hobbiest woodworkers, that are lighter in color than the nitrocellulose lacquer, but not perfectly clear like Acrylic lacquer.

All the above are solvent based lacquers, meaning a lacquer thinner is typically used for clean up and thinning. There are also water-borne lacquers that also go on completely clear and don't yellow with age.

The chemistry for all this is quite complex and is continuously evolving as finish manufacturers try to make their products more environmentally friendly and conform to EPA regulations for VOC emmisions. It gets really confusing and I've probably been guilty, more than once, of over-generalizing the use of terms. My best recommendation is for anyone who wants to learn more about wood finishes and their relative properties, is to get one of 2 books (or better yet, both) that are considered the among the best and most complete descriptions of wood finishes. They are "The Complete Illustrated Guide to Finishing" by Jeff Jewitt and "Understanding Wood Finishing" by Bob Flexner.

[Jan]

Thanks, Bill. That is the answer I was searching for. I did the little experiment because so many had advised that using the Deft lacquers was the answer to avoiding yellowing of the lighter colored woods.

Jan

[Bill Wilson]

I don't use lacquer very much, so I'm not all that familiar with it. Most of what I know is stuff I've read. The key thing is that most of the lacquer that is readily available for the consumer/DIY market is nitrocellulose based and of all the lacquers, it has the darkest color and the greatest tendency to yellow over time. That said, I think where the misperception may arise is due to the fact that NC laqcuer is still much clearer than most oil based finishes and products like Deft brushing lacquer looks milky white in the can, so the presumption is that it won't impart the amber tint of an oil based finish or yellow over time.

Something I would like to experiment with sometime is super blonde shellac flakes. I use shellac for a lot of my scroll work and even some of my general woodworking. Most of what I've used to this point has had some degree of the traditional amber tint to it, but bleached shellac flakes are available as a grade called super blonde and I'd be interested to see just how clear they are.

[HAMMER]

Not that I want to put a kink in your R&D but an old guy told me that there is also a difference between oil based and water based clear stains. Something you might want to test also before it goes into a magazine.... Water based finishes supposedly will have less of a yellowing effect on white woods.

[jim_mex]

Hi Jan - good to see that you haven't lost your investigative spirit.

Bill is the forum expert on finishes despite his modesty on saying he's only read up on most of the stuff and I go along with all he says. I've also carried out a few experiments and done a fair bit of reading and the one thing I can definitely conclude is that it rarely pays to rely on what's written in bold letters on the container of whatever you buy.Worse still, unless you are of a chemical background the fine print doesn't often help.What I've gleaned for sure is that anything that has oil in its mix, whether 'synthetic or otherwise', will eventually yellow to a lesser or greater degree. This is part of a natural oxidating process over time and can't be stopped, only slowed down.

I used to think that the answer to avoid yellowing was to use polyurethane finishes as opposed to oil but I caught a cold on this when I found that a supposedly 'non yellowing' polyurethane did actually yellow over a period of about a year, worse, it had a very strong yellowing reaction when applied over a surface I'd used a white acrylic paint on to give colour to a segmentation project - I now possess a climbing santa with a yellow beard as evidence!!!

For me, the only way I'm confident to avoid yellowing is, as Bill suggests, to use water based acrylic finishes. Don't forget also and any tests that you may wish to carry out need to be assessed over time to really see what is happening.

A good post to resurrect a topic that always gets a lot of questions over, especially by newbies to finishing.

[Bill Wilson]

Thanks for the compliment, Jim. It's much appreciated. Not deserved, but appreciated.

Finishing tends to be the one aspect of woodworking that intimidates most folks. We spend hours designing, prepping material, laying out, cutting and assembling to end up with wonderful works. Finishing is the icing on the cake, the final step that really makes our work shine (bad pun intended). But it's the one that most of us tend to dread the most. Finishing can be complicated, but no more so than any of the other operations we do to complete a piece. I don't claim to be an expert, far from it. But I do know of several sources to find expert advice and I'm willing to share that with anyone who is interested.