Weathering Grade 2

[Lorin Searing]

Silverweathering stain is designed to mimic the look of aged, silver wood. The finish will wash away within the first couple of years, leaving you with a beautiful and consistent gray-silver color. The color will continue to change and patina over time. Delivered ready to install.

The silver weathering stain should be used in exterior applications only and is based on the Cape Cod gray aesthetic. It is designed to be maintenance-free as it develops a bleached coastal patina over time. The stain has two components. One is a silver pigment without binder that will wash off within the first year. The second is mineral ferrous sulfate that reacts with tannic acid in the wood to develop a natural silver color.

We include touchup oil to match face color on end cuts, notches, and rips. This siding product should never be scraped, sanded or pressure washed. A very weak TSP or soap solution, neutral pH cleaner, or simply clean water, can be applied with a cloth or soft brush to wash off pollen, dirt, dust, etc.

Exterior siding should be hosed down regularly to keep it clean and appearance fresh. Use a hammer to tighten up loose fasteners over time as required. Add face fasteners if needed to maintain a flat wall plane. For more detailed installation and maintenance guidance, see our Installation Guidelines.

Weathering categories A, B, and C are used by the Meteorite Working Group at the NASA Johnson Space Center in Houston for Antarctic meteorite finds, denoting minor, moderate, and severe rustiness of hand specimens. A different scale can be set up from the weathering effects seen in polished sections with the microscope. These weathering effects finally lead to the disintegration of the meteorite; they are important in connection with its terrestrial age and an estimate of the true fall rate of meteorites. In order to avoid confusion with the hand specimen classification A, B, C, the weathering grades determined on polished sections were named W1 to W6. Weathering affects first the metal grains, later troilite, and finally the silicates. The following progressive stages can be distinguished: W0: No visible oxidation of metal or sulfide. A limonitic staining may already be noticeable in transmitted light. Fresh falls are usually of this grade, although some are already W1. W1: Minor oxide rims around metal and troilite, minor oxide veins. W2: Moderate oxidation of metal, about 20-60% being affected. W3: Heavy oxidation of metal and troilite, 60-95% being replaced. W4: Complete (>95%) oxidation of metal and troilite, but no alteration of silicates. W5: Beginning alteration of mafic silicates, mainly along cracks. W6: Massive replacement of silicates by clay minerals and oxides. More or less massive veining with iron oxides can already be found in stage W2. These veins develop independently from the weathering grade, apparently in cracks that form through mechanical forces. Broad cracks are often filled with carbonates. Grades W5 and W6 are rare. The silicate alteration affects first the olivines; it starts inside the grains, not from the rim. In stage W6 intact chondrules were found, where olivines were completely replaced by a mixture of clay minerals and iron oxides, the feldspathic mesostasis being unaffected. A correlation between these weathering grades and the terrestrial ages was shown for meteorite finds from Roosevelt County, New Mexico [1]. In these climatic conditions the weathering grades W2 to W6 develop in the following times: W2, 5000 to 15,000 yr; W3, 15,000 to 30,000 yr; W4, 20,000 to 35,000 yr; W5 and W6, 30,000 to >45,000 yr. Similar terrestrial ages were found for chondrites of these weathering grades from the Lybian and Algerian Sahara [2,3]. Antarctic meteorite finds weather much more slowly. A check of 53 Antarctic ordinary chondrites (of hand specimen weathering categories A to C) showed only 9 of grade W2, the rest being W1. Among the W1s is ALHA77278 (category A) with a terrestrial age of 320,000 yr [4]. References: [1] Jull A. J. T. et al. (1991) LPSC XXII, 665. [2] Jull A. J. T. et al. (1990) GCA, 54, 2895. [3] Jull A. J. T. et al. (1993), this volume. [4] Nishiizumi K. et al. (1989) EPSL, 93, 299.

Meteorite weathering is the terrestrial alteration of a meteorite. Most meteorites date from the oldest times in the Solar System and are by far the oldest material available on our planet. Despite their age, they are vulnerable to the terrestrial environment. Water, chlorine and oxygen attack meteorites as soon as they reach the ground.

The most known weathering scale is based upon the effects seen in polished thin sections of chondritic meteorites and it ranges from W0 (pristine) to W6 (heavy alteration). It was proposed by Jull A. J. T. et al.[2] (1991) and updated by Wlotzka[3][4](1993) and Al-Kathiri et al.[5](2005).

The Meteorite Working Group at the Johnson Space Center uses weathering categories AB, C and E to denote the alteration of antarctic meteorites.[1]Their official definitions are:[6]

Weathering is related to erosion, which is the wearing away of rock and earth by natural forces. However, erosion generally means that bits of rock and earth are carried away from their original location. By contrast, weathering leaves the main area of rock in place.

In chemical weathering, the minerals that make up the rock are changed. Water usually is involved in chemical weathering. Elements in the water may react with the minerals in the rock. The minerals may break down or form different minerals.

Biological weathering results from the actions of living things. The roots of plants may reach inside rock openings. Over time, they may push apart sections of rock. Lichens grow on rock surfaces or within cracks. They may wear down rock or etch patterns on its surface.

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For instance, standard grade 50 steel, also referred to as ASTM A572-50, is composed of carbon, manganese, phosphorus, sulfur and silicon. It is a high-strength, low-alloy steel with a tensile strength of 65 ksi and a tensile yield of 50 ksi. Check out the chart below for more details.

Weathering steels are also high-strength, low-alloy steels with a carbon content of less than 0.2 percent, which produces adequate formability and weldability. Most weathering steels are also composed of manganese, phosphorus, sulfur, silicon, nickel, chromium, copper and vanadium. Weathering steels have a tensile strength of 70 ksi and a tensile yield of 50 ksi.

Weathering steels are designed to provide enhanced mechanical properties and resistance to atmospheric corrosion. When exposed to outdoor elements, weathering steels naturally develop a protective patina layer, which is produced by the particular distribution and concentration of alloying elements within it. The patina regenerates continuously when subjected to weather to guard against corrosion.

Weathering steels are a family of ASTM specifications and several trademarked specifications exhibiting similar corrosion-resistant properties. The ASTM specifications include A588, A242, A606-4, A847, A871-65 and A709-50W. The primary trademarked product is Cor-ten, which is United States Steel Corporation (USS) trade name for an atmospheric corrosion resistant steel. The selection of a particular ASTM weathering steel specification is dependent on the type of product desired. For example, ASTM A588 covers structural shapes, plate, and bar while ASTM A242 covers steel plate through one-half inch in thickness.

Weathering steel is available in various grades, specifications and shapes and can be used in a variety of applications. Some types of weathering steel are better suited for certain applications, so knowing the right type to use for your application can save time and money on additional processing.

Established in 1981, Central Steel Service, Inc. specializes in the distribution of High Strength Weathering, High Strength and Abrasion Resistant Steel products. Contact an experienced sales representative, and we can help you determine the best type of steel for your project.

Water is often the main cause of weathering, either as rain or ice. Rainwater can easily enter cracks in rocks or sidewalks. If this happens during cold months, the water may freeze and expand in the crack. Working as a wedge, the ice splits the rock. Many times, road crews have to patch up potholes caused by weathering from ice.

Wind can also cause weathering. Over long periods of time, wind can wear away rock and carry tiny pieces of the rock to new places. This is can create amazing landscapes, such as rocks that look like mushrooms.

Sometimes living things can cause weathering. Plant roots can wedge their way in between small cracks in rocks. As the plant grows, the roots increase the size of the crack little by little. Eventually, pieces of the rocks break off and get carried away by wind or water.

Water is a common way that pieces of the Earth are moved to a new location. Wind also contributes to erosion by blowing the particles away. Glaciers can pick up pieces of the Earth and drag them to new locations. They are slow but powerful.

Although erosion has helped shape some of the most amazing features on Earth, it can be harmful to the environment. When soil is washed away from one place to another, it can carry harmful materials like chemical, fertilizers, or pesticides. These dangerous chemicals can pollute our water supply.

It is important to remember that when weathering happens, tiny pieces of the Earth do not disappear. They are moved through erosion, and deposited somewhere else through deposition. It could be very close, only a few feet away, or it can be many miles away such as if the tiny pieces were washed into a river.

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