Advanced Wood Coloring: Waterfalling

  Anytime we apply color to a single elevation of millwork we lay out the pieces in their proper sequence and apply color to the face side of all pieces of the elevation at the same time. This allows us to color match adjoining pieces perfectly, avoiding problems later in the finish process. This process works better with spray applied stain but should also be done with wiping stains. 

 Sometimes there is variation in the color of the wood which requires the additional step of a toner after the sealer. These panels are also laid out in sequence (waterfalled) so our color is perfect.

  Many beginners try and stain each piece randomly and finish that way as well. Later after the finish is completed and they assemble the casework they find to their horror that many doors don't match. There is a light door next to a dark door. Both doors when held up to the sample match acceptably but one is a tad light and one is a tad dark. Place them together and we have a big problem.

  On a closed coat finish we can scuff sand and tone to blend them together but on an open pore finish we could fill the grain too much causing more problems. This is really critical on flitch matched wall paneling.

  Waterfalling eliminates all these problems and saves much time by eliminating costly toning and refinishing at the end of the job.

The Importance of Samples

  The single biggest problem I see on wood working web sites is people plunging into finishing their favorite woodworking project without a clue as to what they are doing!

  They invariably buy some cheap pigment homeowner stain from the hardware store that is close to the color they are looking for and proceed to smear it all over their project, only to find it is too light and they put on another layer hoping to get it darker, or else there is sanding scratches from improper sanding and glue marks that leave light marks where the stain doesn't penetrate. Now there is a post on a web site asking for help. Sometimes there are even multiple coats of finish on as well.

  All this can be prevented by making a simple step sample before any finish is applied to the project. First understand the different stains and finishes and become proficient with their application. You should be able to identify a dye stain or a pigment stain simply by looking at it. What sheen will your final project be? Glossy, Flat, Semi-Gloss or Eggshell. Professionally sheen is represented by percentage of reflectance. 0% being completely dead flat and 100% being high gloss.

  Using a piece of scrap wood the same species as your project, first wet the wood with a cloth dampened with solvent. (Mineral spirits works fine for this) Note the color of the natural wood. Making a stain is the process of adding color to the natural color of the wood to get the color you want.

  Make sure the sample is sanded or hand planed exactly the same as your project, this can profoundly effect stain penetration which effects color and blotching. I usually put a strip of 2" tape over the raw wood at the end of the sample and then apply my stain. When dry apply another strip of tape, right next to and slightly overlapping the first, to cover the stain. Same thing for each step all the way up to the final coat of finish.

 Don't cheat! You want to see exactly what the final product will look like. If you're happy then and only then do you proceed to put finish on your project. If it isn't right, start over from the beginning and change what isn't correct.

Here is a small step sample I made for a faux finish over a urethane cast molding for a restoration job. From the right end is the urethane, a base color, gilsonite stain and then a glaze of Van Dyke Brown and Black

The Difference between Dyes and Pigments

From the Keystone website:

"Many dyes and pigments are produced from the same building block chemistries, such as anthraquinone, azo, phthalocyanine, and a variety of other chemistries.

 The chemical make-up of dyes allow them to pass into their liquid state when introduced to solvents (water, alcohol, MEK, etc). The solvent molecules effectively work their way into the crystal lattice of the dye and surround the individual molecules of the dye. The solvent eventually separates the individual dye molecules in the solution, which essentially puts them into their liquid state. The final processing steps of dyes are what dictate the type of solvents they will be soluble in. For example, sulfonation will create a dye molecule that typically has water solubility. Other reactions will create dye molecules that have solubility in other solvents, but it is important to note that each dye chemistry will have its own limitations as to the degree of solubility or what is called the saturation point.

 The chemical make-up of pigments allows them to never be broken down into individual molecules, but rather they stick together in small clusters of solid state material. The solvent doesn't work into the crystal lattice of pigments, and therefore they are only held in suspension when incorporated into a liquid system. These suspended pigment systems are often referred to as dispersions, because the chemistry of the entire system is designed to disperse the pigment into the system and hold it suspended in the system.

 Pigments are often treated on the surface, so they will have improved dispersion or suspension capabilities, which allow them to remain stable in a particular system for a longer period of time. There are also methods of grinding pigments to reduce the particle size, and this particle size reduction can also be beneficial for improving the pigments ability to remain suspended or dispersed.

 In conclusion, the major difference between dyes and pigments is that dyes have solubility in some type of solvent and pigments do not have solubility. It's much like the way salt and pepper respond when they are placed in water. The salt will be soluble in the water and therefore dissolve, but the pepper will not be soluble and you will see the pepper floating in the water. The salt would be similar to the function of a dye and the pepper similar to the function of a pigment."

 So for us normal people, if you see something separated out in the bottom of the can it is pigment. Dyes don't come out of solution.

Spraying Dye Stain

We spray the majority of the stain at our shop and a large majority of that is alcohol based dye stain. 

There are two different methods for spraying dye stain, a wet application for open pore woods like oak and dry application for blotch prone woods like cherry and maple. On flat line spray systems sometimes you need to mimic a wiped stain with a spray application and I like to use an NGR stain that will mix in acetone like Sherwin Williams S61 or Keystone Nerosol and mix the stain with acetone and water. The more water in the mix the deeper the stain will penetrate the pores. Usually 2 to 3 parts acetone to 1 part water works very well.

 

Mixing Dye Stain

  We use a large amount of dye stain at our shop. I like to use a gram scale to make my colors when matching samples, this gives me a very accurate formula that myself or any of the other finishers can use to make batches of stain from 16 oz to 30 gallons and have the color be very consistent.

  The scale I am using in the video is a Sartorius explosion proof scale made specifically for the paint industry.  For a small shop or home a smaller gram scale would be fine. They come in all sizes and price ranges.

  We use Keystone Nerosol dyes at our shop but this system is fine for all liquid and powdered dyes as well as UTC pigments.

  I will be doing a step by step video on how to go about matching your own colors in the near future.

Inspection

One of the biggest problems most finishers have is they don't inspect the wood surface as they are white wood sanding. Solid wood comes from the shop with mill marks from the planer, wide belt sander and dents and scratches from handling. Veneer panels have gaps in the seams and also suffer from dents, scratches, veneer tape and glue. If these are not completely sanded out before stain or finish it will require sanding the stain or finish back to bare wood and potentially sanding through thin veneers to the substrate.

  I have always used an inspection light of some kind even if it is just sunlight coming through the shop door at a low angle early in the morning. I bought several of these battery powered, rechargeable inspection lights online and they work great. 

  When you find a defect it is important to circle it with a pencil so you know where it is when you go back to sand it out. It is also very important not to just sand in the area of the defect or you will sand a low area that will be visible in the finish. I use a block and feather the area out over most of the panel and then use my inspection light again to assure it has been removed.

Here I have just orbital sanded a walnut veneer panel and am inspecting for any remaining 

defects before block sanding out the 180 orbital sander marks.

Introduction

 I am nearing the age when I will be retiring from the wood finishing industry and decided I would like to give back a little of what I have learned over the years.


  I read many posts from amateur and professional wood finishers that are extremely uninformed as to the basics of wood sanding, staining and finish application.

   I am creating a series of videos that cover the basics of what I have learned from many years of making stupid mistakes in the hope that it will prevent others from taking that same difficult path.

  I haven't made many videos so I will apologize in advance for the mistakes I am sure to make and hope they will at least be good enough to get my point across.