우드스테인 이란? (WIKI의 정의)

 우드스테인은 용제나 수지 등에 조색제가 분산되거나 녹아있는 형태로 만들어 졌다. 이러한 분산제로는 물, 알코올, 석유화합물 또는 쉘락이나 락카, 바니쉬 혹은 폴리우레탄 같은 실제적인 마감제등이 될 수 있다.  폴리우레탄같이 색상이 첨가된 마감제는 목재의 공극속으로 일정 정도 밖에 침투하지 못하며, 마감재 자체가 노화되거나 의도적으로 제거될 수 있는 특징이 있다.

 조색제로는 안료나 염료가 사용되며, 이 두 제품의 가장 큰 차이점은 입자의 크기에 있다. 염료의 입자가 매우 작아, 전색제에 녹아들어 가는 반면 안료는 상대적으로 입자가 매우 커 전색제내에서 녹지 않고 분산되는 특징이 있다. 염료는 체리나 단풍나무 같은 나뭇결이 매우 섬세한 목재에 사용될 수 있는 반면에 안료는 그렇지 못하다.  이러한 세밀한 나뭇결을 가지고 있는 목재들은 그 공극이 너무 작아 안료들은 그 공극에 잘 접착되지 못한다. 

 스테인의 타입에 따라 나뭇결을 강조하기도 안보이게하기도 한다. 시중에 유통되는 스테인의 대부분은 안료와 염료가 같이 혼합되어 있으며, 이 혼합의 정도에 따라 스테인이 목재에 어느 정도 지속되는 지를 결정지어 준다. 안료는 비록 분산제의 성격을 가지고 있음에도 밀도가 높은 목재에 색감을 많이 내주지 못하나, 소나무류같은 공극이 큰 목재에는 깊은 색감을 낼 수 있게 해준다. 또한 염료는 투명인 반면, 안료는 불투명이다.

젤스테인은 페인트와 비슷하게  침투성을 거의 가지고 있지 않다.

  

A wood stain consists of a colorant suspended or dissolved in an agent or solvent. The suspension agent can be water, alcohol, petroleum distillate, or the actual finishing agent (shellac, lacquer, varnish, polyurethane, etc.). Colored or 'stained' finishes, like polyurethane, do not penetrate the pores of the wood to any significant degree and will disappear when the finish itself deteriorates or is removed intentionally.

Pigments and dyes are largely used as colorants. The difference between the two is in the size of the particles. Dyes are microscopic crystals that dissolve in the vehicle and pigments are suspended in the vehicle and are much larger. Dyes will color very fine grained wood, like cherry or maple, which pigments will not. Those fine-grained woods have pores too small for pigments to attach themselves to. Pigments contain a binder to help attach themselves to the wood.

The type of stain will either accentuate or obscure the wood grain. Most commercial stains contain both dye and pigment and the degree to which they stain the appropriate wood is mostly dependent on the length of time they are left on the wood. Pigments, regardless of the suspension agent, will not give much color to very dense woods but will deeply color woods with large pores (e.g. pine). Dyes are translucent and pigments are opaque.

Gel stains are more akin to paint and have little penetrating ability.

구성

 스테인은 다른 페인트류와 마찬가지로 안료, 용제 및 바인더의 세가지 주성분으로 이루어져 있으나, 다른 페인트류에 비에서는 안료(혹은 염료)와 용제의 비율이 높고, 상대적으로 바인더가 적게 들어가 있습니다. 섬유를 염색하는 것과 마찬가지로 우드스테인은 목재나 기타 재료들에 색상을 첨가하기 위한 목적으로 만들어 졌으며, 반투명하게 하여, 소재가 잘 보일수 있도록 만들어진 것이다. 투명바니쉬나 코팅제들은 스테인 이후에 마감되어 진다. 기본적으로 우드스테인인 표면에 도장막이나 필름을 생성하지 않으나, 페인트나 바니쉬에 사용되는 종류와 유사한 바인더가 사용되는 스테인의 경우 필림이나 도장막을 약간 형성하기도 한다.

Composition[edit]

Stain is composed of the same three primary ingredients as paint (pigment, solvent, and binder) but is predominantly pigment (or dye) and solvent with little binder. Much like the dyeing or staining of fabric, wood stain is designed to add color to the substrate of wood and other materials while leaving the substrate mostly visible. Transparent varnishes or surface films are applied afterwards. In principle, stains do not provide a surface coating or film. However, because the binders are from the same class of film-forming binders that are used in paints and varnishes, some build-up of film occurs.

Comparison with paint and varnish[edit]

The initial application of any paint or varnish is similarly absorbed into the substrate, but because stains contain lower amounts of binder, the binder from a stain resides mainly below the surface while the pigment remains near the top or at the surface. Stains that employ metallic pigments such as iron oxides usually are more opaque; first because metallic pigments are opaque by nature, but also because the particles of which they consist are much larger than organic pigments and therefore do not penetrate as well. Most wood stains for interior uses (e.g. floors and furniture) require further application of varnish or finish for protection and gloss. Stains are differentiated from varnishes in that the latter has no added colour or pigment and is designed to form a surface film. Some products are marketed as a combination of stain and varnish.

Siding Stain[edit]

Siding stain is one variety of wood stain with very high viscosity (others can be quite thin). Effectively, siding stains are paints that do not cover as well and do not form a hard film. They are designed to penetrate better and contain binders that are softer and more flexible, allowing them to last longer than harder, more brittle paints. Siding stain protects against solar radiation especially UV radiation, water, fungus including mildew, and insects. Different siding stains are distinguished by the appearance they impart to wood. Certain solvent-based or oil-based siding stains contain small amounts of paraffin wax, which cannot be painted over, although re-staining is still possible.

Absorption[edit]

Applying stains can be very easy or very difficult depending on the type of substrate, type of stain, and the ambient conditions. Fresh, "green" lumber accepts stain poorly, while aged wood absorbs stains relatively well. Porosity of wood can vary greatly, even within the same piece of wood. End grain and bias-cut grain are far more absorbent, thus will accept more pigment and will darken considerably in those areas. The hard ring may absorb differently from the soft ring. The characteristic medullary rays in oak will absorb much less and remain mostly blonde. Woods that have been heavily subjected to paint strippers or washed down with detergents or solvents will have an increased open grain and accept substantially more stain than normal. Woods from different species of trees can have huge variations in how well they take stain. Different wood species stain differently—the overall color and shade is a result of a combination of the stain and properties of the wood. For example, although medium-to-dark stains tend to look blotchy on maple, they get deeper and more glowing on cherry, with a more consistent coloration.[2] Stains that are fast drying will be difficult to apply in hot weather or in direct sunlight. Stains that are slow-drying will be difficult to work with in damp and cold conditions due to a greatly lengthened evaporation and curing period. New lumber, such as pine, can have waxlike sealants put on at the mill that will prevent proper staining; stripping or sanding the surface may be required. White stains composed of metal oxides, namely titanium dioxide and zinc oxide do not penetrate well and remain on the surface. In such cases, wear easily reveals unstained wood. They are also fairly opaque.

Preparation[edit]

Typically, a thorough final sanding of the wood with one suitable grit will "even out" the absorption of the stain. White stain on a bare softwood or oak floor might require a final 'prep' sanding by hand with an orbital/vibrating sander with 80 or 100 grit, whereas certain hardwoods might be orbitally or hand sanded with 220 grit and higher for a darkish organic stain on furniture. Though it is not as durable, "garnet" is by far the preferred sandpaper for hand-sanding bare wood; first because it is a sharper and faster cutting grit, and second because it does not impart color from the grit, as aluminum oxide or silicon carbide can do. Other methods include "rubbing" with rottenstone etc.

In certain cases you need to clean the wood or remove existing stains prior to staining the wood with a commercial stain in order to avoid damaging the wood. This can be the case for both unfinished[3] and finished wood.[4]

Cleaning Stained Wood[edit]

There are special consideration when cleaning stained wood. One of the most common stains is water stains on stained wood. Techniques to remove the water stains have been documented that use a hot iron[5] to remove the water stain.

Special caution should be used when trying to remove stains from a stained wood to avoid damaging the original stain. This is especially important with antiques.