Art Treehouse Newsletter – April 2019

News About Artist Materials & Techniques!

Laughing Gas & Iron Oxide Pigments

Iron oxide pigments are essential to the artist’s palette, covering a color range from black to green to red.  They oxidize rapidly, and have always been extremely popular.  However, iron oxide pigments do more than just impart color.  They also influence properties such as viscosity and dispersibility. It is possible to have two pigments that appear to be the same color, but have very different working qualities. At this point in time, there is a very high demand for micronized iron oxide pigments due to increasing demand for consistent high quality and performance – but production and supply problems have also increased.

Globally, China and India are the largest producers of pigments for industry as well as for artist paints.  It is well known that more than 50% of all synthetically produced iron oxide pigments come from China.  However, there are two recent problems that have resulted in significant price increases for Chinese pigments.  First, US tariffs have been raised significantly.  This has meant that India has actually been raising prices to match the price of Chinese pigments!  Second, China has been enacting strict environmental regulations on pigment production, especially in the coastal regions.  As a result, the number of iron oxide manufacturers has been steadily decreasing. The Chinese government has enacted a “National Green Plant” certification for pigment manufacturers who conform to new environmental guidelines.  The primary emission they are targeting is unfiltered laughing gas, emitted by the traditional Penniman production process for red iron oxide pigments. Some plants are rushing to implement a new Ningbo process that would reduce the emissions by as much as 7.6 million metric tons of CO2-equavalents each year! If this implementation is successful, it would mean the reduction of this greenhouse gas would amount to the total annual CO2 emissions of around one million Chinese citizens!

Mike Strickland and “Bio-Thinner”

“As an artist who is very sensitive to the traditional solvents used in oil painting, I have been searching for an alternative for a number of years. The first replacement I tried was acrylics…”  Read more HERE.

Authentic Natural Products

Recently, some artists have emailed us pointing out there are several manufacturers selling Oil of Spike Lavender that is diluted either with petroleum solvents or petroleum derivatives.  There is really only one way to tell for sure that a product is genuinely natural – radiocarbon C-14 testing.  The Art Treehouse Oil of Spike Lavender has now been analyzed for Natural Product Authenticity by the University of Georgia Center for Applied Isotope Studies, and they have concluded that it has “no addition or dilution with fossil fuel derived material”. The CAIS is the international gold standard lab for the emerging field of biobased product determination using the ASTM D6866 specified method for testing.

Biocides and AcrylicsBiocides play a major role in keeping acrylic paints and coatings free from microorganisms that cause them to deteriorate and become unusable.  One of the most common biocides in acrylic artist paints is methyl isothiazolinone (MIT) – one of the biocides facing particular challenges. Global regulatory agencies are becoming increasingly stricter, limiting the number of biocides available on the market. It has become extremely expensive to develop a new biocide product, get approval, and conduct all the mandatory tests and studies.  Many of the biocides used at this point have already had their approval revoked or will no longer be approved in the future. 

Image attribution: Ajmorrill [CC BY-SA 3.0 (]

As always, there are many interesting articles about artists and techniques on The Art Treehouse web site – including Mark Balma’s “LEONARDO DA VINCI’S Painting Techniques”.