Ammonia fuming

Ammonia fuming is a technique used to darken wood surfaces; some research information about which species are mostly affected is reported here:

https://www.researchgate.net/publication/235767240_Application_of_Natural_Dyes_in_the_Coloration_of_Wood

A Black Locust sample and a Sumac sample were sanded to 3000-grit and then subjected to chatoyance measurements at various fuming stages. This chart summarizes the results:

Note: the last point on each curve corresponds to a final shellac coating.

Pictures below show the appearance of the Black Locust sample:

After sanding – PZC = 27.2
2 hrs fuming – PZC = 33.6
4 hrs fuming – PZC = 34.5
6 hrs fuming – PZC = 34.3
10 hrs fuming – PZC = 31.2
14 hrs fuming – PZC = 31.1
18 hrs fuming – PZC = 29.4
26 hrs fuming – PZC = 24.5
34 hrs fuming – PZC = 22.0
46 hrs fuming – PZC = 22.7
70 hrs fuming – PZC = 19.9
92 hrs fuming – PZC = 19.9
92 hrs fuming + 2 shellac coats – PZC = 18.3

Pictures below show the appearance of the Sumac sample:

After sanding – PZC = 23.7
2 hrs fuming – PZC = 24.5
4 hrs fuming – PZC = 25.3
8 hrs fuming – PZC = 26.5
12 hrs fuming – PZC = 27.0
16 hrs fuming – PZC = 26.9
24 hrs fuming – PZC = 25.9
32 hrs fuming – PZC = 23.4
44 hrs fuming – PZC = 24.0
68 hrs fuming – PZC = 20.9
90 hrs fuming – PZC = 19.4
90 hrs fuming + 2 shellac coats – PZC = 21.9

Pictures below show an additional sample that was also subjected to northern Italy direct sunlight exposure:

Initial (3000-grit sanding) – 26.0 PZC
After 3 days fuming – 23.4 PZC
2 Shellac coats – 26.3 PZC
After 47 days in late spring sunlight – 26.3 PZC

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