I have here a selection of Holbein Aqua Duo paint swatches that I had made into a personal lightfast test for my own evaluation. I had hesitated posting this since it's only a small set of the paints Holbein offers, and a few of them have been changed apparantly since then. Nontheless, it may give an idea of how reliable Holbein is, assuming you trust my testing procedures.
Two separate sheets were painted at the same time, one sheet taped to a south facing window, and the other placed in a drawer for 12 months as of September. That window gets quite a bit of sun and we didn't have too many overcast days this past year. On several days when the weather was nice I placed the window samples outside on the balcony in direct sunlight. I generally don't leave them exposed outdoors or in a car like some others do since I feel that may introduce other factors to the test other than just light exposure, like temperature and humidity.
Blue Violet:
Green Blue:
Ivory Black:
Lemon:
Marine Blue:
Permanent White:
Raw Sienna:
Red:
Sepia:
The colors on the left are the drawer samples (D), and those on the right are the window samples (W.) The top swatch is a masstone (straight from the tube) and below that is a tinted swatch of that color mixed with @ 50% of their "Permanent White." To their immediate right is a diluted sample of each swatch. The surface is Multimedia Artboard paper.
Blue Violet (Dioxazine) = PV 37 (Renamed Dioxazine Violet) - LF rating 4/4
Green Blue (Phthalocyanine) = PB 16 - LF rating 3/4
Ivory Black (Ivory & Carbon) = PBk 9 & PBk 7 - LF rating 4/4
Lemon (Monoazo Yellow & Titanium White) = PY 3, PW 6 (Blick now lists different pigments for Lemon Yellow) - LF rating 2/4
Marine Blue (Copper Phthalocyanine) = PB 15 (Renamed Phthalo Blue) - LF rating 2/4
Permanent White (Titanium [mixed?])= PW 6 - LF rating 4/4
Raw Sienna (Hydrous Iron Oxide) = PY 43 - LF rating 4/4
Red (Monoazo Naphthol) = PR 188 (Discontinued, their Naphthol Red is now PR 170, which is more yellow) - LF rating 2/4
Sepia (Bituminus Earth & Ivory Black) = NBr 8, PBk 9 (Blick lists different pigments now) - LF rating 4/4
These "LF ratings" are lightfast numbers that Holbein had posted for these particular paints at that time. The scan above is oversaturated some compared to the actual paints, but the overall results were good anyway, which is why I mainly wanted to show them.
Changes from these compared to what Holbein now offers:Blue Violet is renamed Dioxazine Violet. Marine Blue is now Phthalo Blue. The Lemon Yellow offered on Blick's site has a completely different listing of pigments than my Lemon. Red is no longer available. Sepia has a different pigment list on Blick's site than the Sepia I have. (The pigments in this test are those listed above.) Note that they sell both a Titanium White and a Permanent White with both listing only PW6 as the pigment. It's possbile Permanent White may be mixed with zinc, hence the different name. On the label of Ivory Black I have it lists both PBk 9 & 7, but Blick lists only PBk9, so I don't know if the contents have been changed but it shouldn't matter much.
End Result:Personally, I can't see any difference between the window or drawer samples, which by my measure means they all pass as lightfast. I was curious how the "Red" would hold up since it's the most saturated and essentially a dye, but it performed very well. The Lemon and Marine Blue also had a low ratings, but they all look fine to me.
It's a good idea to do your own tests like this as you collect new paints just to satisfy your own peace of mind, or find others who have done them. If anyone buys the changed colors Holbein now offers, I'd be curious to see similar tests on them, if I don't get there first. I hope you find this useful, and feel free to start a thread for the other brands. 6 months is often long enough to start to see any problems, but 12 months will likely give you the best range of sunlit days.