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Painting Furniture & Casework, No place for "Latex Paint"
 
Painting Furniture & Casework, No place for "Latex Paint"
Created by Steve on 11/1/2014 5:25:45 PM


Painting Furniture and Casework
Not a place for "Latex Paint"


I would like to thank Fred Hargis for the following question that I received by email.  It has prompted me to sit down and finish an article on a topic that frequently came up, both at Hardwood Lumber & More... and during the time I was host of the WOOD Magazine Finishing & Refinishing Forum.  Fred wrote:

"I wonder if you could help me understand something.  I often suggest to folks that they avoid using latex paint on their projects; specifically bookshelves and such things.  I mention that if they need to stay with a water borne finish they should use an acrylic enamel.  Here's where it goes beyond my meager chemistry knowledge.  Some acrylic enamels are labeled "acrylic latex", which sometimes prompts more confusion.  I think the difference may be "acrylic latex" as opposed to "vinyl latex", but really do not know.  Is it that simple?"

Thank you, Fred, for your question.  You asked: “Is it that simple?”  Yes…and, no!  In the following, while attempting to avoid getting lost in the tall grass of finish marketing, I will try to explain why we must exercise great care in the selection of water-borne paint for use on furniture, cabinetry and casework.  I wish it were as simple as just saying no to “latex paint”.  But, as illustrated by your question, products labeled as “latex paint” cannot easily be distinguished simply by what is printed on the label.  I will say at the outset that if a painted finish is your objective a far better choice would be a quality oil-based paint, or even milk paint if it will give you the look that you want.  But, there are localities (even entire states) where oil-based paint is no longer an option.  And, even with a product as simple as milk paint we cannot always rely on the label as explained here.  With that in mind I will try to help you identify water-borne paints that will produce acceptable results and avoid those that will not.

The problem is “Blocking”

When selecting a finish we should avoid the marketing hype printed on the label and in the sales literature.  Instead we must be concerned with the actual properties of our finish options.  Properties such as hardness, abrasion resistance, resistance to common household chemicals, moisture resistance and heat resistance as they relate to the expected hazards of daily use to which the item being finished will be exposed are critical.  When selecting paint another property that should always be considered is resistance to blocking.  All of these properties are important for us to consider.  But, resistance to blocking is a crucial consideration when painting furniture on which we expect to set other items.

Simply defined, blocking is the tendency of paint to stick to another surface that comes in contact with the painted surface.  For example, a painted door, even after the paint has fully cured, is closed against a seal or gasket around the door opening.  When the door is opened the paint from the door sticks to the gasket.  That is an example of blocking.  A more pertinent example in this discussion occurs when an object (not necessarily a heavy object) like a hardcover book or a vase is set on a painted shelf or tabletop.  When, after as little as a day, the item is picked up the paint sticks to it.  This, too, is blocking.  Heat and humidity can aggravate the problem. 

Blocking is a common occurrence with “latex paint” and will be the focus of this article.  In Fred’s question, in addition to latex he mentioned, vinyl and acrylic both of which are resins used in the production of finishes.  Resins, of course, are the things that actually produce the finish film.  At the risk of over simplifying the process, resins are either dissolved in a solvent or suspended in a binder, depending on the nature of the finish.  It is the solvent or binder that provides the liquid content and makes the finish easy to apply, whether by brush, spray or pad.  Without this liquid content (referred to as the volatile component because it evaporates and adds nothing to the actual finish) it would be virtually impossible to transfer the resin (the solids which actually produce the finish film) to the surface being finished.   When the solvent or binder evaporates what is left behind is the resin film (the coating).  All of this would be very easy to understand, including what finish should be selected in which application if finish manufacturers would be more forthcoming in identifying the content of their finishes.  But, alas, that is not to be.  All too often it is left to the consumer to cut through the hype in order to make an informed decision. 

So, with that in mind, let’s begin with the deception at hand and attempt to clarification some terminology.  There really is no such thing as latex paint if we presume that by the inclusion of the word "latex" in the name the intent is to communicate that there is actually latex in the can.  In truth, there is none!  For those of us who are familiar with the marketing of "Tung Oil Finishes" this will come as no great surprise.  None of the popular “Tung Oil Finish” products contain any tung oil.  In the minds of the marketing folks the name is justified simply because someone in the marketing department has decided (who knows based on what) that the finish looks like tung oil.  Much the same rational has apparently crept into the marketing of latex paint.  Latex, after all, is a cloudy white liquid that "dries" clear.  Water-borne acrylic finishes also exhibit a milky appearance in the can, but dry clear.  So clearly (no pun intended) it is appropriate to call these paints "latex".  Now, I'm at a loss to understand why the properties of latex, a plant resin used in the production of natural rubber, would have been deemed desirable when associated with paint; but, I never understood why Valspar thought describing their original polyoneverythane as "liquid plastic" was a cleaver move either, except possibly that the 50's were the age of plastics.

But, I digress.  If there is no latex in “latex paint”, what is the ingredient that causes me to strongly suggest that it should only be applied to walls and ceilings; never to furniture and other casework?  If we can identify the problem ingredient we can simply eliminate from further consideration all paints in which the ingredient is used.  Unfortunately, it isn’t that simple.  In general, the term “latex” has become a bit of a synonym employed in the marketing of most water-borne paints.  Some of these paints employ only acrylic resin while others contain as little as 20% or less acrylic resin.  If you sense that acrylic resin may be the key to quality, you are correct. 

Acrylic resin is expensive to produce.  It can cost over twice as much to produce compared to other synthetic polymers such as vinyl acrylic, styrene acrylic and polyvinyl acetate (PVA) the main ingredient for white glues and virtually all cheap (really cheap) latex paint.  Given the reality that for many consumers the dominant consideration is price, the competition for shelf space in Big Box retailers and even your local paint and hardware store means that there is considerable pressure on manufacturers to utilize less expensive ingredients to keep costs down.  When coupled with the reality that attractive packaging and focus group selection of product names trump consumer education it should come as no surprise that labels don’t tell us much; and, for many of us, our decisions begin and end with price absent any compelling reason to the contrary.  Against this background, the typical interior “latex paint” found in retail outlets is composed of 20% or less acrylic resin and 80% or more one of the less expensive to produce resins.  Unfortunately there is no requirement that the word “vinyl”, “styrene” or PVA appear anywhere on the label.  Now, in fairness to both manufacturers and retailers, the target application of these paints is not furniture; it is walls and ceilings, applications in which we expect to repaint (redecorate) at regular intervals.

Let me change direction just a bit.  Forget paint for a moment and let’s focus instead on applying a clear coat finish.  Again, for reasons of durability, I prefer oils or even shellac; but, there are a number of water-borne acrylic finishes that do acceptably well in the face of heat, abrasion, common household cleaners and water, both liquid and water-vapor.  In the case of these water-borne clear coat finishes, all of them (at least those with which I am familiar) are 100% acrylic, though some marketed as “polyacrylic” and similar names do contain very small amounts of urethane resin.  Acrylic resin finishes offer superior attributes, relative to their ability to withstand common hazards of daily use, when compared to “latex paint” formulations that contain other synthetic polymers.  These include:

1.    Much better resistance to water and water-vapor leading to surfaces that can be cleaned without damage

2.    Significantly improved adhesion and abrasion resistance which leads directly to better resistance to blocking and scratching

3.    Improved resistance to alkali cleaners

We now come to the heart of the matter.  I have often made the point that a quality oil-based paint is little more than a quality oil-based alkyd resin varnish with pigment added to produce an opaque color.  Similarly, a quality water-borne paint (we will call it “latex paint” if we must) is little more than a quality water-borne acrylic finish with pigment added to produce an opaque color.  Quality oil-based paints are formulated with alkyd resin to prevent them from “yellowing”.  Quality water-borne paints are formulated with acrylic resin to prevent them from blocking and to impart the other properties listed above.  The use of vinyl (“vinyl latex”), styrene (“styrene latex”) or polyvinyl acetate (the stuff in PVA glue) is virtually guaranteed to result in blocking (to say nothing of poor abrasion resistance, resistance to household cleaning chemicals, etc.) and extreme disappointment.  If you are committed to the use of a water-borne paint always specify 100% acrylic and ask to see the statement in writing in the data sheet.

I have listed below, in alphabetical order, a few paint brands by product name that are 100% acrylic formulations.  Some use the word “latex” in the product name (though I will never understand why) and some do not.  Please note that this list does not constitute a recommendation of any of these products.  It is simply my attempt to point you in the right direction and help you avoid water-borne paints that will result in much disappointment.

BEHR Premium Plus (Home Depot)

Benjamin Moore MooreStyle Interior Acrylic Latex

Devoe Ultra-Color

Olympic One (Lowe’s)

Pratt & Lambert Accolade

Valspar Medallion

The preceding list notwithstanding I would still urge you, if possible, to avoid using a water-borne paint at all.  You will be much happier with a quality oil-based paint, one based on an alkyd resin formulation and made from soya (soybean) oil.  On the occasions that I have made painted furniture and casework I have used Benjamin-Moore Impervo with outstanding results.  My method of application is to cut-in the inside corners and molding with a natural bristle brush and then us a 3” or 4” short knap roller on the rest.  The result is no brush marks and a like-sprayed finish.

Yet another alternative if you are committed to a water-borne finish and you have the ability to spray is General Finishes White Enduro Pigmented Poly.  This is a water-borne acrylic finish with a bit of urethane resin added to justify calling it “poly” but not enough to impart the more negative properties of Polyoneverythane.  It can be tinted to any custom color.

Hopefully we have been able to eliminate some of the confusion created by the marketing of “latex” paint and its application in finishing furniture and casework.  Unfortunately, this is but another example of why the last place to look for information about finishes in on the can or in the manufacturer’s marketing literature.  “Latex paint” (if we must use the term), in my view, still belongs on walls and ceilings where it is subject to few hazards.  But, if you take the time to find a product that is truly 100% acrylic for painting furniture and casework you will be able to obtain a satisfactory result; not as good as you will achieve with a quality oil-based soy-alkyd paint, but satisfactory.



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