Tell me about wood stain

Definition: a semi-transparent coating that penetrates the wood to provide colour whilst also allowing features of the wood, such as colour and grain effects, to remain visible


How does wood stain work?

Stains come in a wide variety of types, but all include some sort of colouring agent mixed, suspended or dissolved in a solvent or “carrier” substance. This carrier can be oil, water, alcohol or polyurethane.

A stain is a colourant applied to wood to change its colour. Unlike paint, stains are designed to soak pigment into wood fibers with a solvent and then as it sets or cures, the colour binds to the wood.


Types of wood stain (interior)

Oil base

  • almost always formulated with a linseed oil carrier
  • best wood stain for furniture or any large wood surface because of the slower drying time, which gives the piece a more even finish
  • tend to penetrate deeper, leaving behind a richer color that is easy to refresh by applying another coat
  • has excellent surface adhesion that makes the surface resistant to peeling, giving the wood a more durable finish
  • applied with a cloth, rag or foam applicator
  • existing finish needs to be removed before you apply the stain
  • clean-up requires use of mineral spirits; also used to thin the stain

Water base

  • uses water as the binder, which makes it easy to thin
  • offers the best protection against mold and mildew and more environmentally friendly, as they contain less polluted articles
  • perfect for small projects because of its quick drying time
  • does not penetrate the wood as deeply as oil-based stains which results in softer colors; darker colors can be obtained with successive coats
  • can be applied with a brush or foam applicator
  • best applied to raw wood or wood with the existing wood finish removed
  • clean-up is easier; wash with warm soapy water

Gel base

  • in between a traditional stain and paint; thicker than other stains- more like a jelly
  • uses a powdery thickening agent mixed with liquid resins, mineral spirits, or pigments as its binder
  • sits on top of the wood (instead of being absorbed into the pores like water and oil-based stains)
  • designed to make wood finishing easier by eliminating the need for careful brushstrokes
  • give more or less color based on how hard its rubbed into the wood
  • best wood stain for furniture made of pine, cherry, maple or other woods prone to blotching
  • can be applied with a brush or rag
  • adheres well even if the piece is not completely sanded down to the original wood (just needs a scuff sand beforehand)
  • clean-up with mineral spirits

How to prepare wood for staining

There MUST be a proper base in order to have a successful stain. Prep sanding is done with progressively finer grits.

Start preparing the surface by using medium paper first, and then proceeding to finer grades. On most raw woods, start sanding in the direction of the grain using a 120-150 grit paper before staining and work up to 220 grit paper.

  • Soft woods such as pine: start with 120 grit and finish with no finer than 220 (for water base stains) and 180 grit for oil base stains
  • Hardwoods such as maple and oak: start with 120 and finish-sand no finer than #180 (for water base stains) and 150 grit for oil base stains.

A general rule for the use of sandpaper is as follows – the finer the sandpaper used, the lighter the stain color will be.

Do not over sand or you may seal the wood (close the pores) so much that it will not take the finish.


What is a wood pore?

Pores are the result of vessels that conduct sap in a living hardwood tree. (Softwoods are “nonporous.”) When a board is milled from a hardwood tree, these vessels are cut open at various angles, exposing the channels we call pores. Finishers generally differentiate between hardwoods by calling them “open-pored” or “closed-pored” woods. (@finewoodworkingmagazine)

As you sand – working your way from lower grits to higher- the pores begin to close. If you sand with too high a grit before you stain, there is nowhere for the stain to absorb into.

A stain test board showing stain absorption at different finishing sanding grits.
A stain test board showing stain absorption at different finishing sanding grits.
Image courtesy of Uneedainc

How to apply stain

  1. Properly prepare the wood (see above!)

If applying stain to an open grain wood (ex. elm, ash, walnut, oak), you may want to use a pre-stain conditioner to fill the pores in the wood to even out the surface. Think of this like construction workers filling potholes in a road before applying blacktop.

  1. Stir your can of stain thoroughly using a wooden or plastic stirring utensil.
  2. Dip your rag, brush or sponge into the stain and spread it on the wood, working your way across the piece in sections and making sure to go with the grain.
  3. Apply the stain in a thin, even layer using long strokes to brush or rub the stain onto the wood. Focus on making sure there aren’t any major streaks or splatters of stain anywhere on the wood.
  4. Wipe away the excess stain according to the instructions on the product you’re using – remembering that the longer you leave the stain on the wood, the darker it will get. Use a clean rag to wipe off the excess stain, rubbing the wood lightly going in the direction of the grain to dab up the extra pigment.
  5. Let the stain dry for according to product instructions before adding additional coats, if desired.
An example of the process of applying stain

References:

https://www.homedepot.com/c/ab/types-of-wood-stains/9ba683603be9fa5395fab90b89c64a3
https://www.familyhandyman.com/article/types-of-wood-stains-finishes
https://www.bobvila.com/articles/gel-stain
https://generalfinishes.com/instructions/how-prepare-wood-for-stain
https://www.finewoodworking.com/project-guides/finishing/filling-pores
https://www.sandpaper.com/articles/grit-sequence-let-grit-do-the-hard-work-for-you
https://www.wikihow.com/Stain-Wood#Sanding-and-Conditioning-the-Wood


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