A while ago, I made a couple of posts on CRU adjustments to 19th century SST estimates based on their speculations about the use of canvas and wooden buckets. (While I’ve posted some questions about land temperature records, there is a far more pressing need to wade through SST procedures. My earlier posts were here and here. At the time, I quoted Parker, Folland and Jackson  as follows:
Overall global warming in SST between the 1860s and the 1970s is about 0.3 °C greater in the present analysis than in Folland et al. (1984), mainly owing to reduced early corrections applicable under the assumption of the predominant use of wooden buckets (Section 3).
There are some graphics in the original post that are worth re-examining. Today I happened to read Hansen et al 1993 (Clim Chg 25, 186), Commentary on the Significance of Global Temperature Records. It said:
Also, “corrections” for changes in the composition of buckets used to draw the water (IPCC, 1992) are ad hoc and of dubious validity.
Yes, this condemnation was of IPCC 1992 (not IPCC 4AR) , but these adjustments are still used by CRU and IPCC. By the way, Phil Jones did not cite Hansen et al 1993 in IPCC 4AR. Check out my earlier description of the “corrections” that Hansen condemned here and here.
Folland, C. K., D. E. Parker, and F. E. Kates. 1984. Worldwide marine temperature fluctuations 1856–1981. Nature 310, no. 5979: 670-673.
Hansen, J., and H. Wilson. 1993. Commentary on the significance of global temperature records. Climatic Change 25, no. 2: 185-191.
Parker, D. E., C. K. Folland, and M. Jackson. 1995. Marine surface temperature: Observed variations and data requirements. Climatic Change 31, no. 2: 559-600