I would like to build a table with a red top: Cocobolo, Bloodwood, Padauk or Bubinga. I only want to invest the time and money if I can keep the color of the wood (nearly) as red as when it is freshly finished. I presume that the darkening that I have observed is due to UV exposure.
Will ordinary lacquer block the UV or is there a blocker that can be added? Is there some other finish that will prolong the retention of the original color.
Cheers,
Larry
Numerous marine varnishes include an UV blocker. So do lacquers used in photography. In fact, most anything with a yellowish tint will block some UV.
Mahogany stays pretty red, no?
Oxidation and UV exposure are a problem. Apply the finish ASAP after cutting,sanding, or scraping. You can see a difference within 24hrs without sunlight with some woods, within minutes in sunlight. That's not to say that it won't change over time with a finish, but the less time the wood is exposed to air or UV helps mitigate the fading and/or color change. Usually re-surfacing and re-finishing every few years is required for maximum color retention.
Yes, there are blockers you can add or finishes that contain UV blockers or absorbers. Most UV products will be marketed for exterior use. I've heard some references of good results with valspar/lily/guardsmen products with uv blockers. Ucecoat from cytec Clariant interior wood finish uv additives
Another idea, is to produce a dye from the sawdust of the wood and dye the wood that made the dye. Still fades, but the colors are often much more intense to start. I only did this on a whim for pieces with color variations, padauk and bloodwood, when making dyes from them for other pieces, usually aspen or maple, sometimes cherry.
The new Nano tech blockers look good in theory, but I haven't personally seen the results, other than the skin sunscreens. The theory, that seems to be working in the sunscreens, is UV blockers can only block when the particles block the UV rays. When the object is covered thick enough to fully block all UV rays, the blocking agent is visible. This is only good for opaque paints.(or white visible sunscreens) Using nano sized particles it is now possible to fully coat the surface while remaining translucent. We'll know better after a few more years of field testing.
Advertisers often exaggerate or even outright lie, so I wouldn't discount the tech just because one product didn't live up to expectations. The nano particle oxides can be purchased in raw form. If you have a university near you that has a nanotech program, encourage them to mix up a custom finish and do some testing for a school project. A few new tech product links;
While this is true many remain soft, probably not a good thing for a table top.
In the long run it would probably also prove inadequate to prevent darkening.
Cherry darkens naturally to a deep brick red. If that is red enough for you, use a non-darkening finish over it.
ONLY spar varnishes remain pliable; however, any finish with UV blockers that I'm aware of, will "yellow" the surface.
It's just the nature of the beast.
Lew
Cherry was not in the mix of asked about woods and typically is not as red as Padak or Bloodwood. Cherry tends to still have a brown tint.
High Performance Top Coat is the hardest, most durable consumer polyurethane top coat on the market today. It contains all the consumer friendly characteristics of PolyAcrylic Blend. In addition it contains a UV Stabilizer to protect it from breaking down in sunlight and to protect the underlying stains from fading. And with its pure polyurethane durability, it can even be used on floors. This is the most durable product. Not recommended for outdoor use. The product is sold At Woodcraft of Rockler, it is made by General Finishes. Non yellowing.
Ken
The problem as I have read is to have a finish that can actually block the UV light from getting to the wood. Many of the UV protection additives are there to make the finish last longer, not the keep the wood from changing color.
Good post, Joe.
I personally don't know if we will see widespread FULL use of nano technology for a while. However, in line with your earlier comments, it doesn't stop advertisers and manufacturers and their claims. In a true sense of the word as originally used, nanotechnology used in the application of coatings is baloney.
See:
I do believe that they have grabbed the term for their own use, bending a partial definition of "nantechnology" as being one of working with tiny particulates. However, this ISN'T on a molecular level, and to me, that makes it no more than a marketing ploy.
I know that nano technology in coatings does exist and is being used more and more and that it works. But the application of a true nano technology coating is very different as is the end product for the guy that buys "One Coat Premium Sealer - Now With Nano Technology!" down at the local hardware store THAT AIR DRIES.
Maybe Phil and Doug Nano were on the mixing line that day, and used the current technology to add the stearates.
Or maybe they have a new micro grinder that added some crystalline structure to the mix to increase UV or abrasion resistance, but to my knowledge there are no time dry finishes that employ true nanotechnology.
Robert
includes the subfields of study.
The term manufacturers should be using is nanomaterials or nanoparticles, a sub-field of study in nanotechnology.
Hopefully as more people become aware of the advances in the underlying science, the manufacturers will describe their products using more exact terms. "Contains oxide nanoparticles" would be more correct for current stains being marketed, although if nanomaterials are being used I don't think nanotech is strictly incorrect. It just more like saying "There's science in a can", a little broad and capitalizing on a buzzword and therefore potentially confusing consumers. Confusion driving sales has never been something marketing has shied away from.
Maybe. Certainly there are nanomaterials that need specific application to achieve their desired functions. However, that does not discount translucency and solvency of smaller particles of opaque materials suspended in liquids. These should not need any special application to achieve good results. I always grind pigments as fine as possible before mixing dyes. If I don't there will be color blotches. It doesn't have to be so high-tech of an application to equate to a newer, better product.
That's one reason why I put the idea out there. I, like many people, use what has worked for me in the past. Often what I was taught the first time. I'm looking for any experience from those who have the time and money to experiment with the newer tech, whether high-tech or just new mix formulas.
I do quite a bit of glass work and the newer formulas being used have no equivalence with old technology. COE stable glasses, thin film dichroics, stable and predictable colors, many features not possible even 20yrs ago.
I'm looking forward to similar advances in wood technology. Sawstop blade brakes, chainsaw brakes, NC and CNC tech, waterjets and variable focus rotary lasers in the home shop price range, silver ion paints, ceramic microsphere stain resistant paints and many other advances yet to be discovered.
Excerpts from wikipedia which imply characteristics of interest for stains and finishes;
Materials reduced to the nanoscale can suddenly show very different properties compared to what they exhibit on a macroscale, enabling unique applications. For instance, opaque substances become transparent.
Suspensions of nanoparticles are possible because the interaction of the particle surface with the solvent is strong enough to overcome differences in density, which usually result in a material either sinking or floating in a liquid.
Nanoparticles have a very high surface area to volume ratio. This theoretically does not affect the density of the final product.
Reading your post, I agree with your premise of presentation. However, there was an old comedy movie once that said in a fake ad (imagine your radio advertiser's voice here):
"Now you can own this super ball made from the same material used in tires of the B52 strategic bomber that safeguards our country. It is simply amazing. You throw it down, it bounces up. You throw it up, and it comes back down. All under its own power. No batteries needed. Amazing"
That's how the "nano ads" sound to me now. Anyway they can fit it in, they will.
But in one strict sense, simply rendering the particulates to size could include them in a valid definition of "nanotech" nomenclature.
This was one of the earliest attempts to define the technology and its output I could find. This dates to the 80s, although the nano/concept has been around since the 50s.
************************As nanotechnology became an accepted concept, the meaning of the word shifted to encompass the simpler kinds of nanometer-scale technology. The U.S. National Nanotechnology Initiative was created to fund this kind of nanotech: their definition includes anything smaller than 100 nanometers with novel properties.
Much of the work being done today that carries the name 'nanotechnology' is not nanotechnology in the original meaning of the word. Nanotechnology, in its traditional sense, means building things from the bottom up, with atomic precision. This theoretical capability was envisioned as early as 1959 by the renowned physicist Richard Feynman.
*************************You can see the shift in meaning. Now it seems to used for pretty much anything on a microscopic level. But in fact on almost all accounts rendered by the scientific community, "nanoXXX" is regarded as a reference point on an atomic level if not at least the molecular level.
That being said, (and back to woodworking!) I am waiting to see if any of these nano products make it to market soon. I have read about paint that will block cell phone calls for about 5 years now. Never seen it in use. Sure would be nice at the movies, eh? I have read tales of sign companies that can power ad signs and change their messages and colors with nanobots. There were claims of nano technology breakthroughs that could block certain wavelengths of radiation, and UV rays as well while remaining transparent.
It could be interesting days ahead for the coatings industry. Just wish they would speed it up!
The rest of the applications for that technology in medicine, farming, computing (remember the gel drives?), and on and on is just staggering. Real nanotechnology will touch every part of our lives very soon.
Robert
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