Find a clean dish sponge (not a scour pad) and a ballpoint pen with a removable tip.  A cheap, plastic pen works best, as long as you can easily pull off the plastic tip and remove the ink. A slightly see-through pen can make it easier for you to see what you are doing. Use your finger to feather and break up the fibers of the sponge.

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Write a summary of the previous text in Vietnamese:
Thu thập dụng cụ. Chừa lại từ 0,3-0,6 cm bọt biển chìa ra khỏi đầu bút.