Follow along as guest blogger, Doug Murray, goes through the process of refurbishing an old Hamilton drafting table found in a barn! This is part 4, so make sure you start at the beginning with his first post.
Final Sanding, Stain Application and Protective Varnish Finish
Well I’m in this project about a month already and I can kind of see the finish line. I have to remind myself, “Don’t get impatient! This is the point of the project where rushing will cost you greatly.”
I’ll talk a little bit about my finishing process and then explain how the Hamilton desk was fine tuned. After all the repairs and sanding, it’s good to go over every piece with a fine grit sandpaper; 180 to 220 will do just fine. Then take a towel and give all the pieces a good rub to remove all particles and contaminants. Some people like to use a damp cloth, but on larger pieces, it can get a little muddy as you start to pick up more and more particles. That can lead to debris in your stain. The best situation would be a dust free environment, but that’s not very practical in a wood shop as messy as mine!
The important thing is to try and get off as much dust as possible before applying the stain.
For this particular project, because the wood was so old and thirsty, I decided to make my own custom stain to maximize absorption into the wood. In this case I used 1/2 gallon of linseed oil and 8 ounces of turpentine. In order to fine tune the perfect hue for the oak, I opted to add 16 ounces of minwax Golden Oak stain which is readily available in most hardware stores. This concoction was mixed very well with a stir stick and stored in a dedicated container. Remember to mix your stains very well before each application. If you have a multi piece project like me and forget to mix the stain evenly for all the parts, you will notice subtle tonal differences in the final product. Never mix stains with a power mixer or shaker, always slow, deliberate strokes with a wood paddle. You don’t want to create bubbles, they will also affect your overall finish by leaving circular forms when they pop.
One of the benefits of working big is the ability to use large brushes and stain applicators. In this case, I went through about 10 four inch stain brushes. When working with large pieces, try and set your piece on triangular stands or nail beds. These will allow full coverage of the stain without leaving bare spots during drying. I like to stain the unseen side of the boards first and then flip the boards onto their triangle mounts and apply a nice even finish to the side that everyone will see. I’m also a big fan of threading copper wire through screw holes to hang pieces and stain them as they dangle in mid-air.
When applying stain, all of the parts should have an even sheen after application. You should have no bare swatches or pooling areas. Use the stain applicator as a sponge, drying and wringing out excess stain to eliminate any pooling, and filling all bare wood areas. I don’t like to wipe my stain off with a towel after application. I prefer to give the piece 24 hours for absorption and then start applying the varnish.
Varnish can be a tricky bugger. You worked your tail off refurbishing and re-staining, now you have to be very careful. The wrong varnish will cause much loss of sleep! For my desk, I wanted the wood to be the star of the show. In other projects, I prefer a hi-gloss to help accentuate brass work or add another layer of protection. For this desk, the wood grain had absorbed the stain beautifully. It would be a shame to apply a hi-gloss or even a semi-gloss varnish and loose the lovely grains in all the shiny reflectivity.
For my desk, I opted for a Minwax, spar varnish with a satin finish. This will add an exceptional layer of protection to the piece without turning it into a gilded Baroque nightmare! Spar varnish was originally intended for marine use; which means that it’s very durable. While most modern spar varnishes are just cleverly disguised polyurethane, it does wear much better than those products labeled as polyurethane. The biggest difference you will notice is the viscosity. It’s very similar to maple syrup, but don’t eat it! Don’t get any on your hands either or you’ll be smelling it for the next day or so. I like to wear rubber gloves for my varnish applications. If you do get it on your hands, you can rub it off a bit with sawdust.
A word on brushes and varnish. When I use a brush for my final coats of varnish, I try to reuse the same brush as much as possible. I do this by wrapping the brush in a plastic bag very tightly after each use and clamping the bag to a table so it cannot get air. This is a bazaar process I admit, but it works for me for two reasons. First, I don’t like to clean my varnish brushes with paint thinner because residual thinner can affect the viscosity of the next layer. Second, it would be expensive to throw away your brushes between each application. My bag process has worked pretty well for me so far, but if you’re not re-applying on a 24 hour basis, your brush could harden up and become trash-worthy.
I like to apply a coat, allow 24 hours for drying and then finely sand the surface with 220 grit paper. This takes off all the tiny dust particles that land while the piece dries. It also creates a level surface for the next application. This sanding should be very light. Place your hand on the areas before you sand and after, make sure you can feel the differences as the tiny bumps are sanded away. Don’t sand hard, or you can eat into your varnish and get down to the wood. Intense sanding could also remove the stain, which would create a very patchy final product. After sanding, use a dry towel to rub off the sanded residue.
It’s good to apply three coats of spar varnish, sanding between each coat. After the final coat, allow 24 hours to dry and do a final sanding which will pretty much give you a glass-like surface.
While I was at it, I decided to re-paint and varnish all the metal hardware a nice satin black. This included the steel reinforcements on the sides of the desktop. The original hardware had a galvanized grey look and just wouldn’t have done the final piece justice “as-was”. This was one of the few opportunities I had to stray from the original design. This is a risky choice, but in the case of my desk, I couldn’t see it any other way. Traditionalists could scoff at my impudence, but the good news is that if you have to change it back to original design, taking the paint off the hardware is a simple task.
So now I have a random assortment of stained and varnished pieces! Let the jigsaw puzzle construction phase begin!