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Why does wood become darker when it ages?

Why does wood become darker when it ages?


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I have lots of pieces of pine furniture which have different colours depending on how old they are. So, I just wondered why that is. I guess it has something to do with structures and chemical compounds that were already in the wood when it was still alive, so I hope this is not off-topic here.

What processes take place in dead wood when it ages?

What determines the colour it will have? For example, pine and spruce wood looks very similar when freshly cut, but will develop very distinct colours afterwards.

Is there also wood that does not become darker?

Is it something to do with the processing of wood, or will that happen to any stick you leave lying around in your room (so it doesn't rot)?


While most wood we see comes from stain or oils, wood left on its own will darken. As far as this article suggests, this is caused by the polymerization of polyphenols from lignin into tannins which are dark red or brown in color when they are highly polymerized.

The specific content of the lignin in different woods will affect the density, strength and color of the wood.

This woodworking reference shows that intense UV exposure to wood will darken it to give it an aged look.


Why Are Tree Rings Lighter or Darker?

New wood formed in a tree during spring and summer is light in color. Toward the end of a growing season, new cells formed are smaller and have darker thicker walls. The wood is more dense and darker.

That annual pattern creates rings. They tend to be wider in wet, good-growing years.

The thickness and darkness of the dark part (as well as the light part) can vary depending on many things in a given season: precipitation, sunlight, temperatures, and disease and insect infestations, volcanic eruptions and fire.

Near the core of a tree, rings will be tighter and darker if a young tree grows up in the shade a mature forest. Soil conditions that might change over time can also affect the growth.

"The patterns in tree rings tell a story," explains Erin McMurry, research assistant in the University of Missouri'sCollege of Agriculture, Food and Natural Resources Tree Ring Laboratory. "We think of tree rings as ecological artifacts. We know how to date the rings and create a chronology, so we can tell when there has been a fire or a drought occurred and unlock the history the tree has been holding for years."

Tree rings have been used to understand everything from ancient droughts to hurricane activity before records were kept.

McMurry and her colleague solved a longstanding mystery by studying tree rings.

On May 19, 1780, it was black as night at noon. Some people in New England thought judgment day was at hand. Accounts of that day, which became known as "New England's Dark Day," include mentions of midday meals by candlelight, night birds coming out to sing, flowers folding their petals, and strange behavior from animals.

The scientists announced on June 6, 2008 that evidence from tree rings reveals massive wildfires as the likely cause, one of several theories proposed after the event, but dismissed as "simple and absurd."

"A fire comes along and heat goes through the bark, killing the living tissue. A couple of years later, the bark falls off revealing the wood and an injury to the tree. When looking at the rings, you see charcoal formation on the outside and a resin formation on the top that creates a dark spot," said Richard Guyette, director of the Tree Ring Lab at the University of Missouri.


There are a lot of links on this site to information or products I have personally found helpful. Most products are something I use or have used and heartily recommend. Some of these links may be affiliate links which means that I will receive a small commission at no extra expense to you if you decide to purchase something.


The Flavor of the Barrel

More important than the color is the flavor that is added to aged spirits. At the same time, this 'flavor enhancement' mellows out any harsh notes found in the distillate (liquor straight out of the still).

You will often read whiskey reviews that talk about an 'oakiness' or 'undertones of charred oak.' As the spirit is in contact with the wood, it pulls out some of those woody flavors. It is similar to grilling salmon on a cedar plank.

Depending on the wood used in the barrel, you will get different flavors. Woodford Reserve's Master Collection of bourbons is a great example of this. Every year the brand releases a limited edition of the whiskey and the difference is often as simple as the finishing barrel.

For example, they will take the same aged bourbon we enjoy every day and place it in a special barrel to 'finish' it. The Maple Wood Finish from 2010 was decidedly sweeter than the Seasoned Oak of 2009. The barrels for the 2009 whiskey were charred then set outside for 3 to 5 years before filling. The resulting bourbon was far more complex than anything Woodford had produced to date because the wood itself had gone through so many seasonal changes.

It is common for distilleries to play with the types of wood used in their barrels and enthusiasts often look forward to the new tastes. The liquor's flavor will also be affected by the previous use of the barrel.

  • Barrels that previously aged sherry are common in whiskey aging, especially with scotch. These whiskeys may have a sweeter, wine-like tone in the flavor. , so they are unusable by the distillery after the first batch. Many tequila, rum, and other whiskey brands will buy these barrels for aging, giving their spirits flavor notes reminiscent of bourbon. make a point of using unusual woods in their barrels to create distinct expressions of their distilled spirits.

You should get excited when a brand tries to show off a liquor aged in a new barrel, especially if it's one of your favorites. You should try the new-barrel-aged spirit against the standard bottling. It will give you an entirely new appreciation for the effects of aging.

Unlike wines, distilled spirits do not improve with age once they are in the bottle. As long as they are not opened, your whiskey, brandy, rum, and the like will not change and they will certainly not mature further while they wait on the shelf.


Michael Robinson’s tranny conversion into Michelle Obama

Michael Obama is said to have undergone surgery in his late 20s, just before he met Barack Hussein, who knew from the beginning about the real Michelle. Michael was not going to begin that relationship based on a lie, so he told Barack, but he already knew. Their kids are all from Barack’s sperm but they’re surrogates. Michael is “mom” and that’s that.

“When it comes to me, they get really, really ignorant. They believe that just because I have an Adam’s Apple that I’m not a real woman.”

The dead giveaway, when you’re trying to tell someone’s biological gender (that’s called science, by the way), is by taking a look at their laryngeal prominence or “neck triangle.” Commonly known as the Adam’s apple, that’s the protrusion or “lump” formed by a certain angle of thyroid cartilage that surrounds and protects the larynx. For adult males this secondary sexual characteristic is clearly visible and also palpable. This is related to the deepening of the voice, as it becomes accentuated during puberty.

There is cosmetic surgery, called chondrolaryngoplasy, that can be done to reshape the Adam’s apple by reducing some of the thyroid cartilage. But then there’s those big manly shoulders to contend with, when we’re speaking of Michael Obama.

Maybe everyone will think she works out really hard, and so the simplest solution to that cover-up problem is just don’t cover them up, ever. Attention women seeking arms and shoulders like “Michelle” Obama, if you weren’t also born a man, it may be difficult to just work out and develop shoulders like an NFL linebacker.


Contents

Dry rot is the term given to brown rot decay caused by certain fungi that deteriorate timber in buildings and other wooden construction without an apparent source of moisture. The term is a misnomer [2] because all wood decaying fungi need a minimum amount of moisture before decay begins. [3] The decayed wood takes on a dark or browner crumbly appearance, with cubical like cracking or checking, that becomes brittle and can eventually crush the wood into powder. Chemically, wood attacked by dry rot fungi is decayed by the same process as other brown rot fungi. An outbreak of dry rot within a building can be an extremely serious infestation that is hard to eradicate, requiring drastic remedies to correct. Significant decay can cause instability and cause the structure to collapse.

The term dry rot, or true dry rot, refers to the decay of timbers from only certain species of fungi that are thought to provide their own source of moisture and nutrients to cause decay in otherwise relatively dry timber. However, there has been no published experimental evidence to support the phenomenon. [4] In modern texts, the term 'dry rot' is used in reference to damage inflicted by either: Serpula lacrymans (formerly Merulius lacrymans) predominantly in the United Kingdom and northern Europe and/or Meruliporia incrassata (which has a number of synonyms, including Poria incrassata and Serpula incrassata) in North America. Both species of fungi cause brown rot decay, preferentially removing cellulose and hemicellulose from the timber leaving a brittle matrix of modified lignin.

The term dry rot is somewhat misleading, as both species of fungi Serpula lacrymans and Meruliporia incrassata require an elevated moisture content to initiate an attack on timber (28–30%). Once established, the fungi can remain active in timber with a moisture content of more than 20%. At relative humidities below 86 percent, growth of Serpula lacrymans is inhibited, but it can stay dormant at relative humidities down to 76 percent. [5] These relative humidities correspond to equilibrium moisture contents of wood of 19 and 15 percent, respectively.

An explanation of the term "dry rot" circles around boatyards periodically. In the age of wooden ships, boats were sometimes hauled for the winter and placed in sheds or dry dock for repair. The boats already had some amount of rot occurring in the wood members, but the wood cellular structure was full of water making it still function structurally. As the wood dried out, the cell walls would crumble. In other words, the wood was already rotten and as the boat dried, the wood collapsed and crumbled, causing the workers in the yard to determine it was "dry rot", when in fact, the wood had been rotten all along.

Schilling & Jellison [6] note the potential efficiency of these 'dry rot' fungi in growing away from direct moisture sources, although there is no reference for how efficient a brown rot fungus has to be at translocating water in order to be classed as 'dry rot'. Some have suggested the importance of these fungi providing their own source of nutrients as being more significant than providing an adequate source of moisture. Schilling [7] suggests efficient nutrient translocation and utilization, notably nitrogen and iron, may be more distinctive in these species than water translocation. Water translocated in this fashion carries nutrients to the extremities of the organism not, as is sometimes inferred, to simply render dry timber wet enough to attack. Coggins [8] goes into more detail about water movement in Serpula lacrymans.

The perpetual saturation of wood with water also inhibits dry rot, as does perpetual dryness. [9]

Dry rot would appear to be a paradoxical term seemingly indicating decay of a substance by a fungus without the presence of water. However, its historical usage dates back to the distinction between decay of cured wood in construction, i.e. dry wood, versus decay of wood in living or newly felled trees, i.e. wet wood. [10]

'Dry rot' is an 18th-century term that generally described what is now called brown rot. The term was used because the damage was present in cured or dried timber of ships and buildings and was thought to be caused by internal ‘fermentations’ rather than water. This contributes to the Etymological fallacy that dry rot requires less or no water than other species that use the brown rot decay mechanism.

The (London) Times on Tuesday 12 March 1793 carried an advertisement that informs the reader that the British Colour Company, No. 32, Walbrook, London continues to use, manufacture and sell paints prepared with the Oil of Coal, which is of a very penetrating nature, and hardens wood in an uncommon degree protecting it from weather, dry rot and ice. [11]

In the early 19th century the rapid increase in instances of timber decay attributed to dry rot (brown rot) in the British naval fleet brought the term into wider usage. Thomas Wade's 'A Treatise on the Dry Rot in Timber' was published posthumously by the Navy Office in 1815 following his investigation of the matter in ships from various countries. [12] The second HMS Queen Charlotte was launched in 1810 and, when inspected, the timbers of the upper decks were found to be infected with 'the dry rot'. By 1816 the cost of repairs for this vessel had exceeded the ship's original construction cost. [13]

Texts published in the 19th and early 20th centuries also used the term to describe fungi which produced substantial (white-colored) mycelium, including Antrodia (Fibroporia) vaillantii.

Eventually, the term dry rot came to apply to only one or two fungi [ citation needed ] the main one being Serpula lacrymans, in the majority of texts dealing with the subject, predominantly from the United Kingdom. This type of fungal decay subsequently also became known as 'true dry rot'. It has even been proposed to use the term water-conducting fungi in the category of brown rot rather than dry rot. [14] However, although the fungi such as these can transport water, it is disputed [4] that it can use this water to increase the moisture content of otherwise dry wood. Whilst it may be disputed as the citation notes, the epithet 'lacrymans' is derived from the Latin word 'lacrymare', meaning 'to weep' and most surveyors of rotted buildings have noted the tear drops formed by the fungus as water forms on the hyphae. These water droplets are photographed in Rentokil's book "Decay of Timber in Buildings" Figure 24. [15] There is, however, no evidence these small amounts of water on the hypae cause a significant increase in the moisture content of otherwise dry wood.

Dry rot can be very difficult to remediate unless all of the decayed wood and spores are removed. In some cases after this is done, decayed areas can be treated with special epoxy formulations that fill-in the channels of the damaged wood, killing the rot and improving structural integrity. However, this type of treatment can actually promote decay [16] in wood in exterior service unless the epoxy application is designed to shed water. [17] Epoxy or other polymers will trap moisture behind the patch, causing more decay in the surrounding previously uninfected zones unless the repaired zone is protected from recurring water events. Commercial ethylene glycol (commonly sold as antifreeze) and many other toxic diffusible compounds can diffuse into the wood to kill the fungus, but they also can diffuse out of wood that is repeated wetted. Diffusion of these toxic compounds out of the wood, and into surrounding soils and plants is not appropriate from a toxicity or environmental standpoint, [18] and these types of treatment are not recommended for wood in-service. Certain copper compounds, such as copper naphthenate, are available as a brushable solution and are frequently used when dry-rot damage is repaired by splicing in new wood after removal of bulk rotten wood the remaining original surface is saturated with such a compound (typically green in color) before application of the new wood.

In certain buildings, particularly those with solid 9 inch (or greater) brickwork and those built using lime mortar and flintstone, dry rot has been known to travel through and along the wall surface behind plaster and render. It is therefore recommended, by companies that sell this service, that where dry rot is found, plaster and wall coverings should be stripped back to a metre past the infestation in all directions and the whole area treated. However, given that dry rot attacks only wet timber, common sense should dictate that plaster need not be removed where there is no timber or any timber is dry (outside the zone of wetting that caused the outbreak) [ citation needed ] . Identifying the source of water and allowing the affected timbers to dry will kill dry rot, as it is a fungus and requires water as all fungi do. This will not, however, kill any spores left behind, which will remain viable and cause the rot to return upon wetting.


Answer

Chris - Now that's a fantastic question.

It's the same science behind why clothes look a bit darker when they're wet than when they're dry.

The reason that this happens is because when you have paint in the tin, the paint is mixed with some kind of solvent - usually water or oil or something, which makes the paint easy to spread onto the surface so you get a nice even coat.

When you paint the paint onto the wall, it's got all that solvent in it. The solvent then evaporates off - dries - and this leaves behind just the particles of paint on the wall.

Now, the particles, if we take white paint as an example, are usually titanium oxide they're very, very white. These particles are roughly the same size as the wavelength of light, which is why they reflect and scatter lots and lots of wavelengths of light back at you, which is why you see a white surface.

But, when the paint is wet, those particles are surrounded by little droplets of water or oil (the solvent). And so, when light goes in, it doesn't see these tiny particles of roughly the same size as the light wavelength.

Instead it gets subjected to a bit of refraction through the fluid and that buries it deeper into the wall surface, rather than reflecting it back out at you.

So, if it's darker of course, what must be happening is less light is being scattered back towards you than being absorbed and that's why it looks darker.

Once that effect goes away (when the solvent evaporates) and you've just got the particles there, you're scattering more light back at you, so the paint looks brighter.


Blackthorn

Blackthorn, which is a very unusual wand wood, has the reputation, in my view well-merited, of being best suited to a warrior. This does not necessarily mean that its owner practises the Dark Arts (although it is undeniable that those who do so will enjoy the blackthorn wand’s prodigious power) one finds blackthorn wands among the Aurors as well as among the denizens of Azkaban. It is a curious feature of the blackthorn bush, which sports wicked thorns, that it produces its sweetest berries after the hardest frosts, and the wands made from this wood appear to need to pass through danger or hardship with their owners to become truly bonded. Given this condition, the blackthorn wand will become as loyal and faithful a servant as one could wish.


Why do newspapers turn yellow over time?

Paper is made from wood, which is made up mainly of white cellulose. Wood also has a lot of a dark substance in it called lignin, which ends up in the paper, too, along with the cellulose. The exposure of lignin to air and sunlight is what turns paper yellow.

­ Lignin makes wood stiff and trees stand upright. You could say it acts as a glue to bind the cellulose fibers together. It is a polymer, a substance that is formed by the joining of simpler molecules into giant molecules that act differently than the smaller molecules did. Dr. Hou-Min Chang, a professor of wood and paper science at N.C. State University in Raleigh, N.C., compares lignin to the concrete used in buildings, with cellulose as the steel frame. Without lignin, Chang says, a tree could only grow to be about 6 feet tall. Lignin also helps protect the wood from pests and other damage.

Newsprint, which must be produced as economically as possible, has more lignin in it than finer papers. At the mill, the wood that will be turned into newsprint is ground up, lignin and all.

Paper manufacturers utilize the benefits of lignin in some types of paper, though. Brown kraft paper, the dark brown paper used in grocery store bags, and cardboard are stiff and sturdy because they have more lignin in them, and because those kinds of paper aren't treated with bleaching chemicals. It doesn't matter how dark they are because the printing on them is limited.

To make a fine white paper, the mill puts the wood through a chemical solvent process, which separates and discards the lignin. Pure cellulose is white, and the paper made from it will be white and will resist yellowing.

Lignin eventually turns paper yellow because of oxidation. That is, the lignin molecules, when exposed to oxygen in the air, begin to change and become less stable. The lignin will absorb more light, giving off a darker color. Chang says that if newsprint were kept completely out of sunlight and air, it would remain white. After only a few hours of sunlight and oxygen, however, it will start to change color.


Can I Treat or Repair Rotted Wood?

Softwood damaged by wood rot is not salvageable and should be replaced as soon as possible to keep the rot from spreading. If the wood is discolored, but the screwdriver test did not detect softness, you can try treating it. You&rsquoll first have to dry the wood by repairing leaks and/or running a dehumidifier. Once the wood is dry, you can apply a wood preservative that contains copper or borate, such as Woodlife Copper Coat Wood Preservative (available on Amazon). Monitor the wood because it&rsquos still at an increased risk of future rot.



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