Luo shows his calligraphy, copying the style of Huang Tingjian, a Song Dynasty (960-1279) intellectual. [Photo provided to China Daily]

In 2015, he started to make and upload video lessons online, demonstrating how to produce the strokes in regular script, such as the dot, horizontal and vertical strokes.

He has been prolific, having uploaded some 2,000 videos which have been watched more than 1.6 million times in total.

In his videos, he not only shows viewers how to write specific passages, but also teaches them how to make fan-shaped paper upon which to inscribe calligraphic verses and auspicious sentences, or recounts the stories and history behind some of the collections in the Palace Museum.

Luo's original intention for the videos was simple－he has a habit of collecting material about calligraphy, and he wanted to share them with people on the internet.

As well as uploading his library of information, under the pseudonym of Brush Brother, he also took to popular Chinese micro-blogging platform, Sina Weibo, to answer other users' questions about calligraphy.

As time went on, he noticed a pattern of many repeated questions, especially about basic things, such as how to hold the brush, or whether it is best to sit or stand to write. He decided that he would prepare a comprehensive series of lessons.

However, creating such programs is hard work－a 10-second video requires at least half an hour to film and edit. He also has to get up as early as 5 am to record his videos, or there will be too much background noise.

When Luo began his first online calligraphy course, there was no one doing anything similar, so "it was a matter of trial and error", he recalls.

In traditional face-to-face calligraphy teaching, there is one problem: When the students gather around the teacher, only the ones who stand on his left have a clear view of the technique. Viewing from any other angle will result in missing some of the teacher's demonstration.

With online courses, however, that problem disappears. Not only do the videos provide the best perspective all of the time, but students can go back to watch the video over and over again as many times as necessary, to see the way the brush moves across the paper.

In April 2017, encouraged by his fans, Luo started his first paid calligraphy course. Soon, he had more than 40 people sign up to learn from him. Now, each of his courses will attract around 200 students of different ages and professions.