Water-based printing until western printing spread to china. As far as I know chinese painters did not use oil paints until the Manchu dynasty, but to be quite honest, I have not fact-checked this thoroughly.
The "cheap labor argument" is a traditional and not always entirely accurate way to explain the relatively slow pace of technological progress in the roman republican and imperial periods. The reasoning goes more or less like this: roman military expansion during the republic and early empire led to large numbers of slaves being introduced into the roman labor pool, many of them skilled artisans (and intellectuals, for that matter). These artisans are likely the ones who made some of the very labor-intensive art we see from the roman period. Due to the presence of these artisans, and the large unskilled labor pool used in agriculture, mills and mining, Roman society never really needed to invent labor-saving devices to satisfy the needs of the higher strata of society. The ideas were there, and occasionally the technology, but there was no demand for them. The enslaved population continued to remain large after the expansions stopped, since a child born to a slave was the master's property and since slaves were also imported.
With the collapse of roman society in the west, slavery declined (for a number of reasons), and in continental europe more or less was unimporant economically by the year 1000 or so. Many border areas were slower to see a decline, especially the ones plugged into the islamic slave trade, but serfdom provided the agricultural output the elites relied on and the slow rise of urban centres and improvements in rural production techniques led to the use of paid labor instead of slavery. The rapid population growth in especially northern europe seen during the early and high medieval periods kept costs down to some extent, but after the Black Death labor suddenly became very expensive, which meant that late medieval and early modern europe saw a great deal of labor-saving innovation.
This picture is to a large extent inaccurate and has not always been accepted by everyone. We know far less about ancient Rome than we think we do and new evidence keep accumulating of technological developments and the use of labor-saving devices on a relatively large scale, especially during the later empire, in many fields. The roman empire had far more mechanized milling than was earlier believed, for example, and some interesting developments did occur (as it did in other slave societies). Also, there was a lot of technological development before the black death in early and high medieval europe that doesn't quite fit the narrative. Exactly why the empire was never able to produce something like the industrial revolution will remain a mystery and is not a monocausal affair anyway. The truly quickening pace of technological development in europe is a very late phenomenon, after all - most developments made in the early modern period (post-medieval/renaissance to post-enlightenment) build slowly on earlier developments and some technologies remained stable due to technological constraints - europeans were very keen, for example, on building iron breech-loading cannon from the late medieval times onwards, and many attempts and experiments were made from, but these largerly failed to receive a true breathrough due to insufficient metallurgical knowledge and bored bronze cannon dominated european warfare until the rise of modern blast furnaces in the 19th century.