Wednesday, February 18, 2015

Conquering Blotching

 I always find it fascinating in the many woodworking forums I participate in that people have these "rules" for sanding. They always sand to 180 or they burnish with fine grits all the way to even 2000 grit for some of the wood turners. Often fear of the dreaded "blotching" drives this practice.

  I have worked in many very high end finish shops doing fine furniture and architectural millwork most of my life and have never worked in a shop where we sanded any finer than 220 grit and 90% of the time it is 180. This is using both a wide belt sander and a random orbit sander. We have found that 180 grit is the point where the swirls or pigtails from the RO sander no longer show without using a magnifying glass. For very high end jobs and samples I will alway block sand the final pass with the grain to completely eliminate any possibility of swirls. Some other mistakes a lot of people make when using a RO sander is moving it much too fast, pressing down too hard and not changing the paper often enough.

  Trying to make a "rule" when finishing wood is ridiculous because there a LOT of different circumstances you must consider and the final look you are after determines the road you travel down. So for me every different procedure is a tool I can use to match the look I am after as long as I understand how it works, what effect it has on the final finish and the amount of time required to duplicate it.

    1. Wood species: Normally you wouldn't sand a soft species (Fir, Pine or Alder) the same as you would sand a hard species (Hard Maple, Oak or Ash) UNLESS that provides the effect you are after. I have done some antique finishes where the designer actually wanted the wood to look blotchy because that looked more authentic in an aged piece of furniture. The exception is when burnishing the wood actually causes finish adhesion issues, this is fairly common with Hard Maple and the woodworking forums are full of posts where shops have had this problem. I don't sand Hard Maple or any of the hard species of wood any finer than 180 grit. The only exception to this would be on end grain on things like chair arms where I know the stain will penetrate deeper and go dark. I will hand sand the end grain only 1 grit finer and soak the end grain with a little clear solvent that is compatible with my stain. With lighter colors sometimes I don't even apply stain to the end grain and adjust the color if needed after sealing.

    2. Solvent base of the stain: With a water based stain you can actually sand with finer grits than with solvent based stains because the water in the stain actually opens the pores of the wood up and allows proper adhesion of the finish.

    3. Labor hours: In a commercial shop man hours must be kept in check and sanding is the single biggest use of labor. Sanding something all the way through 400 grit is a HUGE waste of time and cuts into the profitablity of the job without providing any addition of quality. In our shop we spray stain on huge jobs of wall paneling in Cherry and other blotch prone woods and have no issues with blotching. We don't use any washcoat, we control blotching by application method only. In my home shop I don't do a lot of sanding at all, I prefer the clean look of cut fibers and do most of my work with a card scaper or hand plane.

    4. The belief that sanding alone can control blotching: Blotching is quite simply the stain absorbing into the softer areas of the wood more than the harder areas. Even if you sand everything to 400 grit the softer areas of the wood will still absorb more than the harder parts. This can be used for effect in species like Anigre and Curly Cherry to "pop" the figure of the wood, nobody calls that blotching. They think the figure is beautiful, yet is is actually controlled blotching.

The absorption of the stain can be best controlled by application method. Applying the stain by spraying you can apply just enough to lightly wet the surface evenly, by not allowing the stain to puddle there will be no blotching. Dye stain works best for this because you can apply the stain multiple times without worrying about adhesion issues.



 For those who don't have access to spray guns the surface can be pre-wet with the solvent of the stain to saturate the softer structure and limit the amount of stain that will soak in. Another option is to use a wash coat of finish to limit the absorption. One of the biggest issues I see with people using a wash coat is that they think there is a standard mix. Samples must be made using different dilutions of wash coat. I will start with a 1:1 mix and go all the way to a 10:1 mix (solvent:binder) on a single board with a strip of masking tape between each one. When I apply my stain I can see the different amounts of absorption and pick the ratio that gets me closest to my desired color with the least amount of blotching. I also find that wiping on a wash coat is a little better than spraying it on when possible. I see people posting about how their stain is now too light after the wash coat. The reason is too much binder or finish in their wash coat. You still want the stain to penetrate into the wood, just not as much.
     
Another thing I see in the photos on woodworking forums is most people don't sand enough or improperly. I see mill marks and scratches all the time. The use of a good inspection light or strong cross lighting is essential for proper sanding. The last thing you want is to apply your stain and find huge scratches or mill marks and have to sand everything back to bare wood and start over. The proper use of an inspection light will eliminate re-sanding. I just mark the defects with a pencil and sand them out.













Monday, December 22, 2014

The Creation of Woodies


   I apply the finish and match colors on custom architectural mill work for rich clients and corporations as a day job. In the course of that work I am exposed to some of the most beautiful wood that exists. Many years ago I began seeing faces in the figure of the wood on custom conference tables we were building and decided to "enhance" the faces so others could see them as well. Most of these faces would occur on veneer panels with the symmetry of the mirror image resulting from the book matching of the leaves of veneer. I discovered I could also make my own book matched wood by re-sawing solid wood in thin sections and gluing them up like they do when making sound boards on acoustic guitars. I made over 100 of these solid "woodies" painting eyes and other things to enhance what I was seeing in the figure of the wood. I sold almost all of these originals in a gallery in Reno, NV. To my surprise and delight everyone saw faces in the wood as well but no two people seemed to see the same things. The most fascinating thing about woodies to me was all the different interpretations everyone came up with and were even willing to argue about what each one actually was to them. That encouraged me to make them more open to interpretation when I created them. Recently I have been creating my woodies digitally. I still have access to amazing wood species and find that photographing the wood grain and book matching the veneer digitally in Photoshop is much easier, allows me to create multiple creations with the same piece of wood and allows more options.

 I have several versions of these new digital woodies available online as Fine Art prints on my website: http://rick-mosher.artistwebsites.com/ 


Monday, August 25, 2014

UV Cure Finishes

I am excited to learn more about UV cured finish systems. We have a large job that requires a UV cured water based clear finish so our shop is investing in a system of lights for our robot and a hand held system for things that can't be finished with a flat line system.

 I am really interested in the Simtec UV cured wood filler. With that product and UV cured finishes I can do a fully filled, high gloss, polished product in ONE DAY! This system is in use for flooring and guitars already. The lights are expensive and confusing with all the different wattage's and wave lengths of UV light.  We are doing some samples now with our coating manufacturer so hopefully I will have some pictures and videos soon.


This is a video from Luthier Tips du Jour 

Saturday, August 16, 2014

Matching Color

 One of the most important things required to be a finisher is the ability to make and match your own colors. Depending on someone else has always been a problem for me whenever I have had to do it. I still have the manufacturer tint my solid color finishes but never have them make stains.

 There are many great places to learn color theory these days. Community colleges have great classes on color theory and color mixing. I have to teach some of our newer people how to mix colors in the next few weeks.

 The first thing I will need to do is determine if the new people can even see color properly and there is a great test online that they will be taking. I tried it myself and it is really good. Usually you take the test using colored blocks that you re-arrange but it is pretty expensive. The online test works very well and is free, give it a try for yourself.



Wednesday, August 6, 2014

Making Wood Work

I have worked at many shops during my career all over the country. Being on the east coast there is the problem of winter. Cold and finish do not mix well. Luckily for me Mark Richey is ahead of the curve when it comes to green thinking. We were the first in the State of Massachusetts to put in a Bio-Mass heating system to use the scrap wood to heat our shop. 


This is our Mawera Biomass furnace

These silos outside Mark Richey Woodworking store sawdust and wood waste 
from the plant and feed them to the Mawera biomass furnace


Many shops I have worked for really struggle with the cold weather especially with catalyzed finishes like conversion varnish or pre-cat lacquer. These coatings suffer from cold checking if allowed to get below 60 degrees F for 48 hours after they have been sprayed. The cold stops the chemical reaction and the finish can shatter. The bad thing is it can happen 6 months to a year later. 
Since we have added automation our shop uses 2K urethane exclusively.



Here is our owner Mark Richey cleaning the blades on the turbine last summer.
Mark is a renowned climber and likes using his skills whenever possible.

Tuesday, August 5, 2014

The Flip Side

I like to finish the back side of my samples just as nice as the front. Usually there isn't a lot of time when making samples so I have to be able to do the back fast and still have it look good. On high end jobs I like to use a textured urethane finish. When the client is looking at the front the back feels different and they turn it over. Now they see our company logo. This isn't a big deal on the original job but samples have a life of their own after a job is completed. We have got many jobs off of a finish sample from an earlier job.

The technique for a textured finish is really simple and it is very fast as well. Usually the sample has been primed front and back so the white primer can be used as the base color. I like to use a low sheen for the base usually and a little higher sheen for the texture, just to make it pop.

 For the small texture I use the standard 1.3 fluid tip, turn the air pressure on my gravity cup almost all the way down and just let the speckles hit the sample. For the larger textures like the water drops, I use my 2.8 tip and un-thinned gloss urethane. Here are a few examples:

White primer with black texture


White primer with gloss white texture


Water drop texture


Close up


The range of possible textures is almost unlimited and it is also 
a good way to use up paint colors from previous jobs


Friday, July 25, 2014

Samples Part 2


This is one of the step samples I made. The right side is unfinished so I have a reference to check when the veneer for the job comes in. Sometimes it is a little different color and that changes my stain formula.

These are all the darker color step samples, we keep these for our reference the client never sees these.
I finish all my samples front and back and usually do a textured finish on the back. In this case there wasn't enough time and these are not final samples. When the client has decided what will be used on the job we will make 5 finish samples and get signatures before proceeding with the work.