Home › Forums › Explore Media › Oil Painting › The Technical Forum › St Petersburg Master Class Oils, Langridge, and Maimeri Puro
- This topic has 50 replies, 16 voices, and was last updated 4 years, 9 months ago by WFMartin.
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January 11, 2019 at 2:01 pm #467401
Hi all,
Just to let you know that Jackson’s website are now selling these 3 new oil ranges..
Must tell myself.. I DO NOT NEED ANY MORE PAINT..
Richard
January 11, 2019 at 2:05 pm #761298The St Petersburg Master Class Oils range does have PY32 Strontium Yellow for those that are interested.
January 11, 2019 at 3:28 pm #761280The St Petersburg Master Class Oils range does have PY32 Strontium Yellow for those that are interested.
The pigment is so nice and delicate. I have some of it in raw form. Sadly, it isn’t very permanent.
January 11, 2019 at 3:45 pm #761261The pigment is so nice and delicate. I have some of it in raw form. Sadly, it isn’t very permanent.
Where did you hear that PY 32 not very permanent? Several manufacturers list it as completely lightfast (with possible minimal shifting toward green).
- Delo DelofashtJanuary 11, 2019 at 3:54 pm #761275Where did you hear that PY 32 not very permanent? Several manufacturers list it as completely lightfast ([B]with possible minimal shifting toward green[/B]).
Which is very definition of being impermanent.
From ArtIsCreation:
may turn greenish due to the partial conversion to chromium oxide
January 11, 2019 at 4:17 pm #761281January 12, 2019 at 12:03 am #761262Guess you guys did not read the pigment manufacturers information on the pigment then… the warning about possibility of it turning green is an effect caused by certain chemical exposure. It is still considered lightfast because very specific sets of variables are required to cause the color to change.
Want to know another yellow considered highly lightfast, but in fact will darken in some media or fade when exposed to excessive light? PY 35, happens when the pigment becomes exposed by remove of the binder through the use of solvents commonly used in oil painting. Nothing is permanent or lightfast if the conditions are not right for it, I just suggest we stop trying to make everything out to be less than what it is.
From a chemical analysis point of view, PY 32 seems to be a solid color, though it’s most common use seems to be in industrial coatings which often get exposed to various highly unfavorable conditions (radiation, corrosive and caustic chemicals, and many others).
- Delo DelofashtJanuary 12, 2019 at 12:26 am #761291@Richard P – Thanks for the info. Great that Jackson’s is offering Masterclass.
I use PY32 and have not noticed any color shift in 2 years. It is a very nice lemony yellow.
January 12, 2019 at 10:10 am #761282Guess you guys did not read the pigment manufacturers information on the pigment then… the warning about possibility of it turning green is an effect caused by certain chemical exposure. It is still considered lightfast because very specific sets of variables are required to cause the color to change.
There is a Russian State Standard GOST 11826-77 for artist’s oil paints, a document similar to ISO and ASTM standards. It states that Strontium Yellow oil paint is marginally lightfast and changes color significantly after 5 months of exposure to direct sunlight, from May to September. Manufacturers could make it better than this standard demands, but no means are able to make the paint completely lightfast.
January 12, 2019 at 10:36 am #761292Is this the row of information you are referring to?
There are 3 columns with temperature information. How do you read this table?January 12, 2019 at 10:58 am #761263Roman, it appears that your document is over 40 years old… pigment technologies have improved quite a bit since then and the pigment that was tested for that document may well have been of a poor quality in itself. These issues arise in ASTM and ISO standards as well, except that the standards are revised a bit more often usually.
Further exploration has many manufacturers now days claiming it at a very high lightfastness rating (usually 8 on the BWS).
- Delo DelofashtJanuary 12, 2019 at 10:59 am #761283Is this the row of information you are referring to?
There are 3 columns with temperature information. How do you read this table?Yes. Columns are:
| Paint’s name | Product classification code | Lightfastness or yellowing for white paints | Maximal particle size, in micrometers | Shear stress limit at 20 ± 2 °C, in Pa*10^-2 | Ropiness at 20 ± 2 °C, not more than, in millimetres | Drying time at 20 ± 2 °C, in days to degrees of drying 1 and 5, not more than | Adhesion, not less than, in mm |
It has one X in lightfastness column, later it is specified that paints with one X are marginally lightfast and methods of determining this quality are described.
January 12, 2019 at 11:18 am #761284Roman, it appears that your document is over 40 years old…
The Standard has three revisions and the last one is not so old, but I doubt that pigment’s properties changed significantly. Other Russian paint manufacturers also mark it as marginally lightfast, with one *. Gamma, Podol’sk. Maybe there is a method to improve its lightfastness, like adding Tinuvin light stabiliser, I don’t know if they use it.
January 12, 2019 at 11:34 am #761293Correct me if I’m wrong but is this row referring to Viridian Green? It has only one X so it would mean it is only marginally lightfast. In the artiscreation website, PG18 is mentioned to be quite lightfast. This document has no reference to pigment ids, only names. Is the lightfastness based on the blue wool scale? Or is it some other test?
It appears that there are some differences in lightfastness ratings between the two references.
January 12, 2019 at 12:03 pm #761285Correct me if I’m wrong but is this row referring to Viridian Green?
No, it is PG 8 Nitroso Green. Here you can compare some commercial names with pigment numbers, sometimes it helps, but not much. For example, Volkonskoite a natural mineral which mostly consists of PG 17 Chrome Oxide Green, yet they write it as PG 23 Green Earth. It is indeed Green Earth, but not the same as Glauconite or other minerals.
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