Article in English: TSP, or trisodium phosphate, can damage your skin if you get it on you directly. Put on rubber kitchen gloves to protect your hands. Avoid touching TSP with your bare hands as much as you can. You can find rubber gloves at most home goods stores. Combine 8 tbsp (112 g) of TSP and 1 gallon (3,800 mL) of warm water. Use a plastic bucket that will not come into contact with food later. Stir the mixture until it forms a thin, watery paste. You can buy TSP at most hardware stores. Scrub the paste into your bricks on the outside and inside of your fireplace using your brush. Work from the top down, and apply extra paste to areas with more soot. Scrub at the areas to remove the soot. Be careful not to damage the bricks themselves as you scrub, especially if your fireplace is old. Use a soft sponge to apply warm water all over your bricks. Gently sponge away any TSP residue that is left on your bricks. Rinse your bucket and brushes thoroughly once you are done using them.  If there is still soot left on your bricks, apply more TSP paste and scrub them again. When you're done, remove the dropcloths.

Summary in Vietnamese:
Đeo găng tay để bảo vệ tay. Pha natri photphat với nước ấm trong xô. Dùng bàn chải lông cứng để chà hỗn hợp vào gạch. Lau rửa gạch bằng nước ấm và miếng bọt biển.