Tech Talk: Lightfastness tests – finale

full view of test card at 6 months

sun-exposed half on left

same card – sun-exposed half moved to right

This is the last post for the lightfastness tests of Mission Gold watercolors that I began in mid-January.  For the last month, I had the sun-exposed card in a window that got much more sun and there was even more fading to the dodgy colors.  As I explained in detail last month, the fading was not unexpected because the pigments used in those colors are rated as poor to fugitive.

Since I posted my previous update, I have had several emails from Dennis Kapp, the chairman of the board of the Martin/F.Weber company, which distributes the Mijello Mission Gold watercolors in the U.S.  Needless to say, he was not happy to see my negative review and said he wished I'd told them about my tests so he could have given me newer, more lightfast colors.  Fortunately, I kept the email correspondence I'd had with his employee, starting with the sample set I received in mid-September, in which I'd pointed out that there were problems with the pigments used in the line.  Although she told me in early January that they were beginning to look at lightfastness matters and would update me, I never heard another word until I received Mr. Kapp's first email in late June.

According to Mr. Kapp, Mijello has reformulated 50 of the 90 colors in the line after receiving feedback at a watercolor society opening last year that there might be a lightfastness problem. (I strongly suspect that the feedback to which he is referring was set in motion by my comments to a watercolorist friend during the National Watercolor Society reception in late September last year.  My friend brought my concerns to the attention of a watercolorist friend of his -- a woman who had been distributing sample sets of Mission Gold at the NWS reception. But perhaps somebody else also expressed alarm about the pigments.)

In his first email, Mr. Kapp listed the pigment changes to the paints that I tested. I've checked them against the lists of reliable pigments, and they are all acceptable.  He also explained that they are creating two versions of some colors -- those labelled as "bright" will be less lightfast.

Mr. Kapp tells me that they have been shipping the newly formulated colors to their dealers for about 60 days now and have instructed their dealers to give replacements for any of the fugitive colors, even if the tubes have been partially used.  

I applaud the company for taking this step, but I have to caution you to be careful. Dick Blick is the only major art supply house that is selling Mission Gold, as far as I can determine.  There is no indication that they are selling a reformulated line and the product numbers are identical to the sample tubes I received last fall.  The local art store that carried Mission Gold removed the product after seeing my lightfastness tests last month. They said nothing about being offered the newly reformulated paint that has supposedly been going out to dealers for the past two months.  If you decide to buy this line of watercolors, ask questions and do some research before purchasing.

Here are some ways to check on pigments: both Michael Wilcox's The Wilcox Guide to the Best Watercolor Paints and Hilary Page's Guide to Watercolor Paints are available through online booksellers, although both are now somewhat out of date -- quite a few new pigments have been added to the world of art since they were published.  I also know of two websites that deal with pigments: Handprint and Art is Creation -- Handprint is chock full of information, but the pigment charts on Art is Creation are much easier to read.

I hope you have found this series of posts instructive and helpful. I strongly feel that artists must demand quality materials -- to accept less is to dishonor our time and talent.

Tech Talk: Pigments – Week 2

 Lightfastness -- comparing full strength paint

(bottom half is sun exposed strip)

 

Lightfastness -- comparing tints

(top half is the sun exposed strip)

Two weeks ago, I began testing these Mission Gold watercolors. (See the original post here.) After painting the test strips, I cut the page in half and put one piece in my flat files and the other in a spot that would get direct sun. Following my plan to compare the sheets every two weeks, I put the two pieces together today, first comparing the full-strength strips and then the lighter washes.

There are a few changes at this point, although nothing drastic. As might be expected, the tints (light washes) were generally affected more than the full-strength colors.  Prussian blue faded slightly in the tint, as did burnt sienna -- both a bit of a surprise, since the pigments listed on the tubes are supposedly lightfast.  There was also a slight darkening of the yellow, particularly noticeable at full strength. The tint of Van Dyke brown faded slightly.  Neither of these was unexpected -- the yellow pigment was rated as fugitive by both Michael Wilcox and Hilary Page and the brown is unlisted, but its closest relatives are considered fugitive.

It's worth noting that the sun-exposed strip has had only a few hours of sun a day on the best days and we had 4 or 5 days of deeply overcast weather in the past two weeks. I'll continue to monitor the test strips and will post again when there is more information.

Tech Talk: Pigments

Watercolor test strip

I'm going to do a number of posts on the technical aspects of painting with watercolors. To start things off, I want to talk about paints. I was inspired to begin this series after receiving a couple of sample sets of a new line of watercolors, Mission Gold, a few months ago. I'll talk more later about the color test strip shown above, but first let's talk about how you can check the pigments used in your paints.

The first thing I do with an unfamiliar tube of watercolor is to look on each tube for the pigment information.  These days, all reputable brands of watercolor list the pigment number or numbers on each tube.  I've circled the numbers to make them easy to find on this assortment of watercolors from various manufacturers.

Pigment numbers (circled)

Pigment numbers are in the form PY## for yellows, PO## for oranges, PR## for reds, etc.  Once you have the pigment number (or numbers in the case of a mixed color), you can check several sources to learn more about them.  For years, I have relied on The Wilcox Guide to the Best Watercolor Paints and Hilary Page's Guide to Watercolor Paints.

You can check the raw pigments as well as the ratings for individual manufacturer's paints.  Hilary Page has tested all the paints herself and gives personal ratings, pointing out her favorites in each color, but Wilcox gives the most comprehensive information on the raw pigments -- pointing out pigments that may be suitable for oil or acrylic paints, but not for watercolors. 

There is also an online resource by Bruce MacEvoy.  He has created an exhaustive catalog of information related to watercolor, with a very thorough section on pigment information. By clicking on the color links at the top of that page, you can see every pigment by number along with detailed information about each one. There is an overwhelming amount of material, but for the purposes of this post, the critical thing is the lightfastness rating (Lf), the column at the rightmost edge of the rating tables. Lightfastness is rated from 1-8, worst to best.

 Now back to my color tests.  After looking up the pigment numbers on the paints in my sample sets, I was very concerned because some of them were ranked as fugitive or unreliable by both Wilcox and Page.  However, since this is a new line, neither Wilcox nor Page has tested the actual paints, so I decided to do my own lightfastness tests.  I had 14 unique colors in the sample sets, so I took an 11x14-inch piece of watercolor paper and divided it into 14 equal spaces.  I printed out the color name and pigment numbers in the center of each space and then painted a full-strength stripe across the middle of the paper, with identical lighter stripes on each side of the center. You'll notice I blotted out the paint at the center of the darker colors in order to see the names and pigment information. (I also lifted a stripe down the right side of each color, but that is unrelated to my test for lightfastness. I merely wanted to see how staining each color was.)

I cut the paper down the middle, labelled the backs, and taped one to a piece of acid-free matboard that I set where it will get as much full sun as possible. The other half is sandwiched between two pieces of acid-free matboard and tucked into a flat file drawer.  At present, the daily dose of sun is not great -- a few hours at best -- but my plan is to compare the two halves of the test sheet every two weeks for at least 6 months.

Stay tuned.