Baulk marking pencils aren't actually that great, the markings will wear off fairly quickly. I use an oil based white paint sharpie and it works well: https://www.amazon.com/SAN35543-Sharpie-Permanent-Paint-Marker/dp/B007UH8WV0/ref=sr_1_1?s=office-products&ie=UTF8&qid=1496856502&sr=1-1&keywords=SAN35543. I have used this on Strachan 6811 cloth with success.