Friday, June 21, 2013

Weighing In

There are mysteries in the world, and then there are mysteries to me. I admit that I still have to think twice and speak slowly when I correlate temperature and humidity. I recall looking at the charts that show the relationship between the two and feeling a slight dizzying effect and vision blurring. Maybe I just didn't want to put in the effort. For general green woodworking I get it, wood loses or takes on moisture as it reaches equilibrium with it's environment. If you want wood to dry, put it in a drier environment.

The best way that I came to understand the concept was that when the wood stops losing or gaining weight, it is "air dry", or equal to the moisture in the environment. This got the concept through my skull, and I've even rigged a scale that didn't give me numbers, but let me know when the weight was stable.
But all that has changed thanks to my friend Nick Clayton, who has graciously loaned me a scientific scale. Now I can accurately track the way that my parts lose weight. Of course, my usual rules of thumb still work fine, but it is fun and fascinating to watch the wood adjust. I also plan to do some test with my steamer to see if the wood picks up more weight or loses it through the steaming process and whether my auxiliary water tank affects it. This will tell me if passing the steam through water is adding moisture to the process and aiding in softening the fibers and conducting the heat.

So with my nerd hat firmly in place, I will be looking at the same old processes through a more accurate lens.

I have an exciting announcement! Tim Manney, the fantastic chair and tool maker, has started a blog. Tim is one of the brightest and most talented woodworkers that I know. He has a remarkably broad experience with different types of woodworking and makers and I am very excited that he has started sharing his thoughts. Check him out and leave a message welcoming him, I know you will enjoy it.

Saturday, June 15, 2013

Bullet Proof Finish

I don't think that I have to go very far explaining the troubles that can plague finishing. We all love woodworking and hate finishing. Milk paint has an especially bad reputation for drawing us into some bizarre quantum world where paint mixed and applied the same way can have very different results.

New Milk Paint Results
I've used one brand of milk paint almost exclusively, which I've covered in other posts. It can create a lovely translucent finish, but is plagued by many problems such as a short pot life, lots of filler that needs to be strained out, strange hazy white specks that show up when least expected, trouble retouching and I'm afraid the list goes on. I've stuck with it because of the softness of the paint that allows it to be easily burnished to a high sheen. But after suffering my own traumas and fielding many calls and emails from others with the same trouble, I thought it was time to direct some attention to finding a solution.

The search for a solution pointed me to another brand of paint from The Real Milk Paint company. I've always loved the paint for its rich colors, ease of mixing (no straining), incredibly consistent results, long pot life (two weeks) and rock solid results. I suppose that I should mention that there's no connection between myself and the company.
What I didn't like was the matte finish and density that made it hard to get that translucent glow that I like. Lucky for me, I had a strange job recently reproducing a 200 year old chair that pushed me to play with some new techniques that seem to have surmounted those issues.

I will spell out the basic process here, and then give the blow by blow in the next post or two. I also hope to make a video soon. There have simply been to many folks in the shop lately for me to attempt a video, which would give far too much teasing fodder to my so called friends.

The key to the process is to mix the paint thin and use a very thin coat of shellac to seal between the different colors, and at the end of the process before varnishing.
Ugly Stain and Shellac Seal Coat
 First, I seal the chair by brushing on thinned shellac (one cup of shellac flakes to 3 cups alcohol). The shellac mix should be so thin that you suspect it of just being alcohol. I put some stain in the shellac to stain the chair and let me see where the application is going. Later, I use clean blonde shellac.

Then I paint the chair with red paint twice. The mix is 1 part paint to 2.5 parts water. I gently rub the chair with mirlon pads to remove any rough areas. I also sand any scraped areas to eliminate the raised grain between the first and the second coats. I have found that the shellac seals the first paint coat from raising the grain excessively, bonus. In between each coat of paint, I use the mirlon to rub off any caked up areas of paint, which makes getting a smooth result later easier.

Red Milk Paint
Then I shellac over the red paint. You could use the stained shellac or the blonde here. The next step can and should be applied while the shellac is still soft.

Shellac Coat

Then I paint the chair black, with a similar ratio of paint as the red. You'll notice that paint is a bit slippery on the surface and doesn't melt into the red. The second coat of black should be applied once the first is dried for at least 3 hours.
First Thin Coat of Black Paint

Once the black is dry, I burnish the chair with the mirlon again until it is somewhat smooth.
Mirka Mirlon Pads

It will be tough to get it shiny like the other brand, but that is what the next step is for.

Once the final coat of black paint is burnished, paint one more coat of shellac and then burnish it to even it out.

Burnished Shellac

Finally, apply your favorite oil or varnish. If I want a quick build up, just one coat of Minwax antique oil can do the job.

I know that it sounds like a lot of steps, but it really isn't because the shellac goes on thin and fast. The benefits of control, consistency and ease make this a great finish. And if you like a more matte finish, just skip the last shellac and go straight to the oil.
I did the finish you see here in less than 24 hours and I've done samples this way and run them under the tap after a few hours to see the water bead off.

There is still lots of experimenting to do with the other colors and layering possibilities, but for my most popular black on red finish, I'm sold.