Some time ago, I posted on WOOD Forums the rules I use in my finishing classes --   “Six rules of Finishing.”   I’d like to explore them one-by-one.  Remember, the reasons for finishing are to beautify, protect, and provide a cleanable surface.

 

#1 When you pick any finish, you select an attribute or two you want and you get all the other attributes that come along with that choice.  There is no finish that's perfect for every need.

• Color or lack thereof.  Some finishes add significant color that may be welcome or unwelcome.  Waterlox is very dark, P&L #38 is very light, big box polys are somewhere in the middle.   Shellacs come in a wide range from garnet to super blond.  Water borne finishes can be generally cool, but the manufacturer or user can add some color to get the same effect as what we have become accustomed to.  If you are doing a pickled maple or oak finish, you probably don’t want an amber top coat.   If you are doing a natural cherry finish, you probably don’t want a cool finish.
• Resistance to abrasion, UV, water, other chemicals, heat   Floors, table tops, countertops, toys, or artwork whose major stress is a monthly Swiffer all have different  needs for durability
•  Ability to apply with your skill level -- spray, brush, or wipe  If you don’t have a spray system, you’re pretty much stuck with other methods.  If you are doing a spindled chair or bed, or louvered shutters and have problems with coverage and drips, then a spray or wipe will probably work better.
•  Ability to apply in your in your environment -- fumes, dustiness, temperature, humidity   If you are working in an unheated garage in January, a carport in High Desert in August, Pacific Northwest in rainy season, July in New Orleans, or a spare bedroom, you need to consider your choices.   I had a post-cat finish set off fire alarms once.  Fumes from some finishes need ample ventilation that might not be possible in your work area.  And you don’t want to spray oil-based poly (ask me how I know this.)
• Time to complete finishing -- number of coats, time for each coat to apply and dry, and time between coats.  It’s  two days before Christmas or other time-dependent need, you can’t be putting on a finish that needs five coats with a week’s drying time in between.  Or even oil-based varnish that needs four to seven days application time.
• Repairability  This was really important in the touch-up business.   Stuff happens at the factory, in transit, unpacking, delivery, on the showroom floor, and in the consumer’s home.   It’s important to be able to repair them in ways that does not mean taking into the shop and doing a full strip and refinish.  This may or may not be an important consideration for your work.   In a prior life, I was a software developer for a product sold and supported world-wide.  It was a prime consideration to make the product supportable and repairable by the field force (and also to allow future changes).  There is a rule in software – every program has at least one error and has one unneeded line of code.  By induction, every program can be reduced to one line that doesn’t work.
• Gloss level  Some finishes are available in a variety of glosses, some are not.   Shellac only comes in gloss finish.  If you want something else, you have to hand-rub it.   If you want a see-your-nosehairs-in-the reflection, you almost always have to do buffing and polishing of the finish after application.   (Finishes that don’t rub well (resist abrasion) are not a good choice for this).   If you want something other than a flat, in-the-wood finish, then oils and oil-varnish blends are not going to do it.  Gloss is measured by a “reflectometer” at 60 degrees incident angle.   Glass varies from 0-100.  Most finishes top out at 85+ as their gloss level.   There is not a standard for what is “satin” or other intermediate finishes.   Different manufacturers vary in what they consider satin,.  Some manufacturers even have different “satin” products with different gloss levels.  Most give you a range, for example, for this product, “Satin” is rated at 45-50 (or maybe 30-35)!
• Film thickness  You can build up lacquers very thick.  Oil finishes must be very thin or they get gummy and sticky.  Shellac finishes can crackle if applied too thick.  Poly can look “plastic” when in thick layers.   I once had a customer who faithfully applied some sort of “Teak Oil” annually.  (http://www.popularwoodworking.com/articleindex/teak-oil-oil-doesnt-exist)This was likely just boiled linseed oil, but without knowing the brand, it could be a dozen different formulations. The accumulation was a gummy, sticky mess, embedded lint and dust that if pressed would leave your fingerprint..  I stripped and refinished and when I delivered she asked how often to teak oil it now and I told her, “Never again.”
• Hardness  I’ve seen “house painters” use a can of Minwax Helmsman on a built-in desk top.  Long oil (spar) varnishes are made to be softer and more flexible.   Within a few months, the top was covered with pen impressions.  The doctor owner of this $500k house was not happy.  Likewise, if you want to rub out a finish, you don’t want an abrasion resistant finish.   Slate is hard but easily scratched; tires are soft, but hard to scuff.   Pick what you need.
• Chatoyance  Cat’s eye look.  Depth and shimmer to a finish for a stunning look.  Or not.  Shellac can make even big box pine look stunning.
• Cost  While the cost of finish products is generally small in comparison with time and other materials, you may not want to or be able to spend a lot of money on a product you’ll only use rarely.  Particularly if you have to buy in large quantity and have it go bad before you can use it up.
• Availability  You may not have access to finishes other than what you can find at your local paint or big box store.   Or shipping may be prohibitive in cost or not recommended in winter.  You may live in a low VOC part of the country and just not be able to buy a product without bootlegging from another state.  (not that I would ever recommend this )
• Compatibility with existing finish, if any.   I have had calls where someone applied a finish over an unknown finish and all of a sudden, the underlying finish blistered and softened.   Lacquer, with its strong solvents can do this to oil-based and water-based finishes.   Shellac is safe under or over most finishes.  Some finishes will not adhere well to other finishes – poly and some of the “super finishes” just don’t like stuff on top of them very well.

     

So, if you make and finish a variety of things, consider a variety of finishes.  And consider that one job can use multiple finishes layered on top to combine attributes.  For example, oil or shellac to add color and depth and varnish, lacquer, or water-borne to add protection.

  

Edited May 9, 20179 yr by kmealy

Great information, Thanks!!

Well done, a very good piece!

Gets one thinking Keith.  Thanks for the info.

Thank you for sharing this info again