By Sarah Sands
Test for your application. So runs the common coda that ends
many of our emails and closes our conversations. At the most fundamental
level, it simply means trying out a new material or technique in a way
that closely mimics how you hope to use it. Other times it requires being
something of sleuth and a forensic scientist of the fine arts. In the
pages that follow we will examine some of the basic concepts behind testing
and explain how it can help plan your procedures, solve problems, and
increase your knowledge.
Perhaps the first question is why we would ask you to test in the first
place. After all, dont we already generate Tech Sheets for almost
everything we make? And doesnt our crack Tech Support team stand
ready to answer any question you might have? The truth is, no matter how
thoroughly GOLDENs Technical Support and Labs put materials through
their paces and develop best practices, unique situations inevitably arise
and possible combinations of materials and techniques constantly expand
beyond the horizon of what we safely know. In those instances it is important
to have the ability to examine choices and weigh consequences. There is
also an element of education and ownership at play here. By becoming involved
with your materials at this level you gain more control over your processes
and a greater command of your materials.
Certain basic features run throughout any type of testing and it is important
to establish these at the outset. One of the most essential is the concept
of a control. Put simply, a control is a standard or primary
condition used for measurements and comparisons; for example, an unmodified
state of a material, the initial starting condition of a surface, or even
a desired result you can judge other trials against. A second feature
is record keeping. Keeping accurate records is essential so tests can
be repeated, solutions recreated, or to help us understand your procedures
should you need to contact us.
Common items might include:
- A timeline and accurate description of each step in an application
- Precise list of materials, including any relevant batch codes (see
illustration on right) or purchase dates
- Ratios used in mixtures
- Environmental conditions at the time of testing
- Size of the pieces
- Personal observations
All too often the essential variable will be a small detail the artist
has overlooked or dismissed, so be as thorough as possible. Along with
written notes, other documentation such as photographs, retained wet samples
of the products, and physical examples of any problems or test results,
can all be crucial. And of course, make sure to label everything accurately
and keep all these materials together and stored safely for future reference.
By which point you must be thinking we are simply out of our minds. We
want you to do what? Even remembering to floss ones teeth
might be an easier task. But dont give up yet! Doing even a small
amount of the above will still put you well ahead of the curve.
- The third task is to design the actual tests themselves. Before starting,
decide on your goal and parameters:
- What do you hope to achieve by the end?
- Is the undertaking meant to be open-ended and exploratory or does
it need to be extremely focused with a great deal of precision?
- What are the known variables or properties you intend to test?
Batch codes are located either on the bottom
of a container or printed along the side of
the product's bar code.
Make sure to write these out, being as exhaustive and thorough as possible.
Conversely, are there ones that need to be minimized or ruled out? For
example, you might find you need to control the temperature or have a
surface be perfectly level. These and other questions are essential to
setting the limits and scope of the test. A common mistake is to rush
through this stage. Dont. Taking time at this level will save significant
effort later on and your results will only be useful if the tests leading
up to them have been well thought out and planned. Still unsure of the
best way to proceed? Feeling absolutely convinced your original hunch
that we were completely bonkers is confirmed? Contact us we would
be more than happy to help you with your plans.
Inevitably the moment will come when you will need to create some surfaces
to paint on. Fortunately they do not have to be fancy or elaborate and
usually simple, well-prepared panels or canvases will do (see our Tech
Sheet on Preparing Painting Supports). However, there are
times when these will also need to reproduce the qualities or procedures
you are testing as accurately as possible. In either case, before starting,
create a checklist of materials and each step you will need to take. And
plan ahead for any supplies. It is often critical to use the same materials
and follow the same procedures for each piece in order to limit any variables
as much as possible. In addition, having access to the exact products
used in a problem area ideally from the same container or batch
can be invaluable for troubleshooting. Scale is another factor
not to overlook. Can you get the information you need at the scale you
are working? Testing something on a 12" square panel, for example,
might not give you the information you need for planning a mural. Lastly,
when tests get complicated or take a lot of time it is easy to lose track
of the process, so remember to check off each item only after it is completed.
In the end, keep in mind the very real limits of reliability. Unless
willing to undertake extremely controlled and
thorough testing, over a long period and under various conditions, the
tests will not always guarantee perfect results or dependable solutions.
However, they will still play an invaluable role in uncovering problems,
narrowing down possible solutions, and providing new insights.
Some Basic Tests
In our contact with artists certain topics are constantly repeated. What
follows are some of the most common and useful tests for tackling these
issues, grouped under the following broad headings: General Materials
and Applications, Adhesion, Varnishing, New Media, and Troubleshooting.
General Materials and Applications
Wondering if you can roller-apply a gel on top of a finished mural? Curious
how a texture will look on a piece of furniture? Ready to apply an isolation
coat for the first time to a painting?
A portion of a Product Review Board showing the alternating
black and white bands with samples of GOLDEN Mediums and
Gels, both by themselves and mixed with color.
Stop for a minute and ask yourself: How important is this piece
to me? Do I know what can go wrong? Do I need to be confident about the
results or do I thrive on the unexpected and experimental? Deciding on
the level of risk you are comfortable with is crucial at these moments.
Or perhaps your questions are simply about the materials themselves.
What is the difference between these two mediums? How long will it take
for a ½" layer of Molding Paste to dry? Regardless of the
type of question, whenever trying a new process or product it is important
to familiarize yourself with the properties of the materials. And taking
the time to create practice panels will not only allow you to uncover
unforeseen problems or unexpected results, it will help make sure everything
meets your expectations before launching into an often irreversible process.
They will also form an invaluable reference for future use.
These panels can take many forms, depending on the materials and applications
you are exploring. A useful starting point might be creating a board displaying
the basic qualities for each medium and gel you use; or what us lab folks
have officially dubbed a Product Review Board. To do this,
start with a properly prepared substrate painted with alternating black
and white bands, placing a sample of each gel or medium you use so it
extends over both the black and white areas (see picture). This will allow
you to better gauge the degree of
transparency once its dry. Take note of its thickness, rheology,
leveling, and hardness when fully cured, etc. Next to this, place a sample
of the same product mixed 10:1 with a color. Remember to label each pair
carefully. As you acquire new products you can add to this board or start
a new one. In the end you will have a useful, quick reference for the
basic properties of each material.
Another simple and practical guide is to create a card for each color
you use. Using a palette knife, apply the color full-strength to show
its mass tone, and then scrape the paint over the surface to reveal the
undertone. Next, mix one part color to ten parts Titanium White and apply
this to another section of the card. Not only will this show how the color
looks in a tint but will indicate its relative tinting-strength as well.
Lastly, mix one part of the color to ten parts of a Gel or Medium, placing
this on the card as well to show how the color appears when made more
Beyond these sample boards and color cards there are many occasions when
creating practice panels will help avoid disappointment or even disaster.
Too many large murals, extensive faux finishing projects, or important
paintings are irrevocably ruined because the artist did not take the time
to understand a new material, tool, or procedure beforehand. When generating
these panels it will be important to create the same conditions you will
be confronted with. Working on a smooth absorbent surface, for example,
might not provide the information you need for a sealed rough texture.
Doing small pours on a stretched canvas will not be the same as large
ones on wood.
Cross Hatch Adhesion Test showing GOLDEN White Gesso mixed 3:1 with GAC 200
on an automotive primer. Area on right (a) was tested after 24 hrs,
the left (b) after 48 hrs, and the middle (c) after 72 hrs. Results show
greatly improved adhesion over time and why you need to take this into account.
Will this stick to that? is one of the most frequently asked
questions, and almost always involves points of
transition, places where different materials come together. These areas
can include the adhesion of the primer to the substrate, the paint to
the primer, and ultimately the varnish or topcoat to the paint. It can
also concern the adhesion of various materials being used in the artwork
itself, especially in collages and multimedia pieces where disparate materials
are often brought together. All of these represent junctions where pieces
are at their most vulnerable to delamination.
Most testing for adhesion can be done with a very straightforward and
simple procedure called the Cross Hatch Adhesion Test. This method is
adapted from the ASTM Standard D3359 and requires a minimum amount of
preparation and tools. You will need a single edge razor or X-Acto
knife, masking tape, and a test piece or representative surface. Prepare
your support and apply the materials in the same manner they will be used.
If applying layers that might prove visually indistinguishable, such as
white paint over a white primer or gloss varnish over a glossy layer of
gel, you should also lightly tint one of the products so you can tell
them apart. Let dry for a minimum of 72 hrs. In a space of approximately
2 square inches, score a series of parallel lines about 1/8" apart.
Then score another series (perpendicular) across the first ones, creating
a crosshatch pattern of little squares. By far the most difficult and
critical part is making sure you only cut through the topmost layer of
material. Finally, take a piece of ordinary masking tape, place it over
the section and burnish it well with a fingernail or the back of a spoon,
then peel the tape straight back upon itself at a 180 degree angle (see
above image). If no squares lift off, you have excellent adhesion between
all layers. If a few squares come off but the majority remains, you may
have sufficient adhesion. However, you might want to retest with a longer
period for drying or look to other means to increase adhesion. If most
or all of the squares come off, this suggests adhesion failure and significant
steps are needed to remedy this.
As an example of how this might be used, lets focus on the adhesion
of acrylics to a non-porous surface like glass when varying percentages
of GAC 200 are added to the paints, which is one of the more common questions.
Start with a thoroughly cleaned piece of glass similar to the one you
will work on. Divide this into five equal sections and in the first section
apply the paint as-is. This will be our control. In the other
sections apply the paint mixed with additions of 10%, 25%, 50%, and 75%
GAC 200. Let dry for at least 72 hrs, since we know acrylics only reach
maximum adhesion over time. Afterwards conduct the Cross Hatch Adhesion
Test to each section and record the results. Did any of them have sufficient
adhesion for your needs? If so, does this solution need to be tested for
additional factors, such as the ability of the adhesion to survive changes
in temperature or exposure to chemicals? If not, try the test again using
similar glass that has been etched, sandblasted, or coated with a specialty
primer made for slick, non-porous surfaces.
Common cases where failure to test has led to problems include working
on surfaces that have been previously coated with an unknown primer or
varnish, working on an unfamiliar material, or not taking into account
environmental, chemical, or other conditions that could adversely affect
an initial bond. For example, simple adhesion to glass is one thing; adhesion
that is dishwasher safe is something else. Paint that sticks quite well
to stone might fail if this is part of a fountain that will be submerged
Test panel with rows of various colors and textures.
One section was left untouched as a control. Other
areas show affect of MSA Gloss, Satin, and Matte
Varnishes applied over an isolation coat.
Varnishing is by far the most common subject we are asked about
either with inquiries about procedures or when there is a need to troubleshoot
or fix. While GOLDEN continues to conduct testing around this subject,
there are many things you can do to increase success.
An often overlooked area for testing are the visual changes caused by
the application of an Isolation Coat or Varnish, especially in regard
to the surface texture, sheen, and the resulting value and saturation
of the colors. All of these will inevitably be altered when using either
or both of these materials, so understanding the degree and manner of
change will help you decide which process and product is right for you
and what level of change is aesthetically acceptable. Another major area
is the method of application. There are a variety of techniques and tools
to work with, so figuring out which ones are best can take time and practice.
It is critical these questions are explored and answered before varnishing
anything of importance.
To understand how the appearance of your artwork will be affected, create
several test panels composed of parallel bands of typical colors and surfaces
found in your work (see image above). Eventually you will be applying
a second set of rows perpendicular to these that can explore whatever
variable or method you want to test. Of course, make sure to always leave
one area untouched and clearly mark each section for later
reference. It is also essential to try and limit any variation to the
one variable you want to test. For example, when exploring the effect
of different sheens, dont vary your method of application. That
way you will feel more confident the changes you see are caused solely
by the sheen and nothing else. The same would hold true if testing application
methods. If wanting to see which type of brush works best, or how varying
the dilution of the varnish might effect open time and leveling, keep
other variables at a minimum.
Lets start by testing how different sheens might affect your work.
Take one of the panels you created and divide it into four equal areas.
Remember, one area should be marked as the control and left unvarnished.
Over the other three areas apply either a layer of Gloss Varnish or an
Isolation coat, as discussed in our Varnishing Guidelines. This will assure
that the surfaces are fully sealed and no longer absorbent. Let dry for
24 hrs. Now apply a Gloss, Satin, and Matte Varnish respectively to each
of these areas. After these fully dry divide each section in half and
carefully apply a second coat of each varnish. You now have a useful guide
showing a range of sheens created by 1 or 2 coats of each varnish. Similar
test and practice panels can easily be set up that focus on isolation
coats, varnish removal, comparing spray to brush applications, etc.
New Media and Techniques
Digital print on inkjet canvas cloth showing the rows
of Cyan, Magenta,Yellow, and Black along with
In the ever expanding world of digital prints, book arts, collage, and
multimedia work, materials are often employed that have unexpected or
unknown properties. Compatibility becomes an ongoing concern as these
newer processes and products are combined with traditional mediums. Very
often, because little or no previous testing has been done, you are forced
to deal with many unknowns.
One popular medium many artists are using now is digital inkjet and Giclee
prints. An area often in need of testing is the sensitivity of the ink
or substrate to various products, in particular water or solvents like
Turpentine and Mineral or White Spirits. To accomplish this, create a
test print using the same substrate and inks as the finished work. To
standardize your test and make examining changes easier, we recommend
making a print using bands of the individual inks your printer utilizes.
For example, most common inkjets use a minimum of four colors Cyan,
Magenta, Yellow, and Black while a Giclee usually has up to seven
distinct inks. If space allows, you can also include rows of blends and
mixtures that might be more representative of your palette. It is also
important to create crisp sharp edges between each of these areas so you
can judge if any bleeding or blurring of the inks occur. Once this has
suitably dried, apply the materials you are anticipating using, prepared
and applied in a representative manner, again in distinct rows but this
time working perpendicular to the first ones always remembering
to leave one section blank for your control (see image on right). After
these layers have dried examine the print for any evidence of bleeding,
blurring, or discoloration. Also note any changes to the value, particularly
of darker colors where a gloss or matte coating can create significant
shifts in appearance.
A related test involves seeing how many layers of a particular coating
is needed to seal the print so one can work on top of it without fear
of disturbing the underlying image. In that case, you would first generate
your test print as before. Mask off one area for your control and then
apply one coat of the varnish or protective coating to the rest of the
print. After this is fully dry, mask off an additional section and apply
a second coat to the remaining areas, repeating this process for however
many layers you wish. Once everything is dry you can apply whatever materials
you hoped to use on top and gauge which number of coatings provided adequate
Other mediums besides digital prints also need testing, such as watercolors,
drawings, collages, traditional photographs, oil pastels, and fabrics.
Each of these might require you to adapt the above procedure differently,
although the principles will always be the same: create a test piece,
save or mask an area to act as a control, then create a series of precise
variations involving one variable or material. Some of these tests will
simply to see how applying a new technique or material affects the look
and nature of the medium. This is especially true with something like
watercolors or pastels, where application of a varnish or other materials
is non-removable and can significantly alter the traditional appearance
and nature of these media. Fabric might need to be tested to see if the
dyes are prone to bleeding or how a medium might change its texture. While
oil pastels will need testing for compatibility, adhesion, and whether
materials like varnishes can ever be safely removed without affecting
the wax content.
Troubleshooting has special requirements that can differ from the examples
we have seen so far. In those cases you generated test panels to explore
a material or process beforehand and to avoid unforeseen problems. Here,
however, the problem has already occurred and you need to discover a possible
solution or understand the root cause so an alternative procedure can
be worked out.
Some common examples might be:
- You have applied a matte varnish and are unhappy with how the picture
looks. Would applying a layer of gloss solve the problem by returning
the painting to its original state?
- You sometimes get hazy areas when applying a clear coat of a medium,
but it seems to happen mostly in the winter. Could this be caused by
changes in the temperature or humidity?
- You notice some underlying colors lift whenever applying washes on
top. Would waiting longer or adding additional medium to these colors
All of these are very real situations you might have experienced at one
time or another. When they happen you will need to try and reproduce the
problem as closely as possible. This can be a challenge in itself and
recalling whatever you can about the procedures, environmental conditions,
and the materials you used will frequently be the first step. Afterwards
try to mimic the troubled area as faithfully as you can, creating several
copies whenever possible so you can begin to isolate variables, compare
different solutions, or perfect a particular remedy before implementing
it. Most importantly, have patience; these tasks can be demanding, difficult,
and time consuming to execute.
As a manufacturer committed to the lasting legacy of art we continually
undertake extensive original research and create guidelines for best practices.
But there will always be an equally critical role for you to play in testing
your own applications, where success and failure is often about aesthetic
issues as much as technical ones. And of course, new techniques and materials
will present the artist with their own learning curves and skill-sets
to master. In addition, even when the testing of our own products has
been very thorough, other materials are constantly changing. The primer
that worked wonderfully under our paints last year might have been reformulated
since then and is no longer suitable. Our hope is by giving you the resources
and support to conduct your own testing we can allow you to have more
control and be more involved with the choices you confront. Finally, if
you have decided none of this is for you, that this issue of Just Paint
is destined for the dustbin, still keep our Technical Support number handy.
It will serve as a reminder that, no matter what, we will always keep
testing for your application and be happy to help in any way
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