1. Rationale Behind This Post
2. General Notes on finishing
3. Shellac Notes
4. Lacquer Notes
5. Polyurethane Notes
6. Varnish Notes
7. Gel Stain Notes
8. Dyes and Stains
9. Water-Based Finishes
10. Final Thoughts
12. Related Links
Rationale Behind This Post
In finishing a recent project (replica of an 1810 Stand), I put together the following eclectic collection of finishing notes.
General Notes on Finishing
# — A sealer is used to control blotching (for blotching prone woods). First apply sealer and then apply your finish.
# — For clean-up, use your finishing thinner to clean brushes and rags.
# — Mineral spirits and paint thinner are the same thing.
# — To apply a finish, you have three options: brushing, wiping (rag or staining type pad), and spraying. Brushing is good for both large areas and/or if you want to build up a thick coat. Wiping works well for applying a thin coat and it looks more natural. Spraying is ideal for pieces that are difficult to hold and apply a finish to at the same time.
# — Use brushes with natural bristles (for example – hog hair) for applying oil finishes, shellac, and lacquer. Synthetic bristle (for example – nylon) brushes are used for applying water-based finishes and paints.
# — To avoid runs apply the finish with the surface positioned horizontally, if possible.
# — Regardless of the type finish, I use gloves and work in a well-ventilated area (better safe than sorry).
# — Lower temperatures equate to longer drying times for your finishes. And, higher humidity equates to a longer drying time for your finish.
# — In general, finishing steps required are as follows: sand, seal, stain, and a protective finish coat. My hook for the four steps mentioned above is 3SP (sand – seal – stain – protective coat).
# — For sanding of bare wood, step thru the following grits: 100 – 150 – 220.
# — After sanding, wipe bare wood with mineral spirits to check for sanding and saw marks, which will show up when you finish. Sand away any marks found and recheck with mineral spirits. The nice thing about mineral spirits is that it will not raise the wood grain.
# — I use foam brushes for applying a sealer. A pack of ten foam brushes goes for one dollar (plus tax) at my local Dollar Tree store.
# — Generally a higher ratio of thinner to finish equates to better self-leveling of the finish.
# — Avoid getting finish on areas that glue is going to be applied to.
# — For finishes other than shellac and lacquer, I sand between coats with 320- or 400- grit sandpaper in order to improve the bonding between applied coats.
# — Use denatured alcohol for dissolving shellac flakes and for thinning shellac.
# — Shellac itself is non-toxic. It is used to coat candy and pills.
# — Need a moisture barrier, then use shellac, it makes for an excellent moisture barrier. And, that equates to minimizing wood movement.
# — A coat of applied shellac will usually be dry within an hour.
# — Successive layers of applied shellac will fuse to one another. In addition because of the fusing, it is not necessary to sand between applied coats of shellac.
# — Shelf life of Zinsser canned shellac is 36 months (according to Zinsser when I called on 22-Aug-2013).
# — If you make your own shellac (using shellac flakes), the shelf life of your shellac is approximately six months. The alchemists at Zinsser have figured out a way to stretch the shelf life of their canned shellac out to three years.
# — Be sure to use dewaxed shellac if you are going to use other finishes over or under the shellac. Dewaxed shellac can be used as a sealer under almost any finish.
# — From conversation with the folks at Zinsser’s helpline (telephone #877-385-8155), their shellac is waxed unless the container specifically states otherwise. In addition, the pound cut is three pounds unless specifically stated otherwise.
# — Regarding Zinsser’s SealCoat, which is dewaxed, the pound cut for their SealCoat product is two pounds. According to Zinsser, to thin the SealCoat two-pound cut to a one pound cut, mix equal parts (a 1-to-1 ratio) of denatured alcohol and SealCoat together. Regarding cutting a two lb cut to a 1/2 lb cut, the folks at Zinsser said to mix three parts denatured alcohol to one part shellac (two pound cut).
# — Ammonia and water (equal parts of each) work well for cleaning brushes. Denatured alcohol can be used for cleaning brushes, but ammonia & water works better. Personally, I prefer to use a foam brush; I do not enjoy cleaning brushes nor dealing with the associated chemical solvents.
# — For thinning and cleanup of lacquer, use lacquer thinner.
# — From what I have read, it is not the lacquer itself, but the lacquer thinner required for thinning the lacquer that causes the toxicity. In addition, the thinning is required in order to be able to spray a lacquer finish.
# — Strong odor and very flammable
# — Dries quickly
# — Self leveling
# — Successive layers of applied lacquer will fuse to one another. In addition because of the fusing, it is not necessary to sand between applied coats of lacquer.
# — Easy to repair and recoat.
# — Mineral spirits (or paint thinner) used for thinning
# — A very popular finish, designed originally for floors. In other words, it is ideal for high wear surfaces.
# — The finish to use for moisture and durability protection
# — Can be applied over any finish
# — To achieve dull look sand or use steel wool
# — Thin cuts key when applying polyurethane
# — To thin start with a 1-to-1 ratio of polyurethane to mineral spirits
# — More coats give you more depth
# — Use 320- or 400- grit sandpaper to sand between applied coats of polyurethane.
# — Mineral spirits (or paint thinner) used for thinning
# — Easy to apply, but more coats are required to achieve the same thickness of fewer applied coats of polyurethane.
# — Thin using a ratio of one part canned varnish to one part mineral spirits.
# — You can apply varnish by brush or rag, and depending on the look you want, you can leave excess on wood, or wipe or brush excess off.
# — Allow to dry overnight.
# — Sanding with #320 or #400 grit sandpaper between coats of varnish is recommended.
# — At least three to four coats generally required
Gel Stain Notes
# — Use mineral spirits (or paint thinner) for cleaning whatever (brush, pad, or rag) you have used to apply your gel stain
# — Not recommended to thin gel stain since the thinner will change the consistency of the gel stain from a mayonnaise thickness to that of a liquid. You would end up changing your stain from a gel stain to a liquid stain.
# — Use to make wood darker (but not lighter in color).
# — Gel stain is used to control blotching (for example – pine, cherry, birch, and maple).
# — Seal wood with a sealer (for example, a 1/2 pound or one pound cut of shellac – two coats) and then apply gel stain.
# — You can apply gel stain under or over any other finish.
# — Gel stain is a thick liquid similar to mayonnaise in thickness. Due to the thickness of gel stain, it does not penetrate the wood to any extent, which in turn helps in controlling blotching.
# — Wipe applied gel stain off with a dry towel. Trying to use the pad used to apply the gel stain to wipe off the excess gel stain just smears the existing gel stain around, some gel stain will be removed, but not much. Note — gel stain dries fast.
# — Since gel stain stays close to the surface of the wood (not much penetration) best to provide a protective coat over the gel stain finish to keep the colorant from being worn off.
Dyes and Stains
# — Dyes are considered better than Stains for tight grain woods.
# — Dyes color the wood without hiding the grain lines and stains highlight the grain lines of the wood.
# — As a general rule, apply dye and then apply stain since dyes soak into the wood whereas stain pigments tend to sit on top of the wood for the most part.
# — If you want a darker colored wood, then you should apply first a dye and then apply a stain.
# — Dyes are absorbed by the wood and react chemically with the wood to change the actual color of the portion of wood that absorbs the dye.
# — To protect the stain coat/s it is best to apply a protective coat such as polyurethane over the last coat of applied stain.
# — Unlike mineral spirits, water and water-based finishes will raise the grain. However, water and water-based finishes only raise the grain one time. Therefore, when using water-based finishes, it is best to wipe with water first and then sand the wood before applying your water based finish.
# — Water-based finishes use water as their solvent. Now that is nice from the standpoint of not being toxic, but it takes longer for water-based finishes to dry because of water being the solvent.
# — If you want a finish that is not going to change the color of the wood, than you should use a water-based finish.
# — Sand between coats (use 320 or 400 grit). Because of the water base, never use steel wool. Since any steel wool fibers left on your finish will rust overtime.
This collection of finishing notes is by no means all-inclusive, but it does provide basic information regarding finishing. I find it handy to have around, and hope you find it worthwhile as well.
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Until next time, Take care
A Primer on Solvents – Popular Woodworking Magazine
Is lacquer thinner the same as paint thinner
UNDERSTANDING WOOD FINISHING – – Understanding_Wood_Finishes.pdf
Finishing for First-Timers – Popular Woodworking Magazine
Selecting a Finish – Fine Woodworking Article