Many acids are very soluble in water. Most of those are easy to remove. Boric acid, however, is a solid and it is not very soluble in water at room temperature. To make matters worse, the longer it sits, the more difficult it can become to remove it, since boric acid can gradually decompose by dehydration into substances even more difficult to remove. Since it is a hazardous substance, take appropriate safety measures, especially regarding inhalation of boric acid “dust.”
Vacuum or sweep boric acid solid from floors and hard surfaces while wearing a facemask. Use a vacuum bag capable of collecting fine particulate. Wear rubber gloves to finish cleaning up using the bucket, washcloth and hot water with a little dissolved washing soda — a teaspoon or two. The washing soda (sodium carbonate) assists removal by chemically dissolving boric acid residue.
Vacuum or sweep carpets with loose boric acid on them using the same process, but, if necessary, follow up using a carpet cleaner that produces steam. Boric acid is more soluble in hot water, so the steam facilitates its removal. It may not be necessary to use the carpet cleaner for only a very limited area. Instead, follow up with the bucket, gloves and warm water. The washing soda will not be necessary.
Pour some hot water containing washing soda on tile or other appropriate hard surfaces, and allow it to set for several minutes if the boric acid is firmly attached or aged, resulting in decomposition products, mentioned above. Then using the cloth or the sponge, get this liquid up. If necessary, repeat this process as many times as necessary. Give a final rinse then allow to dry.
Boric acid, effective and safe when properly used, is nevertheless toxic and requires appropriate safety measures. Avoiding inhalation and ingestion are especially important. As boric acid is used to kill roaches, and so may be found on floors, perhaps behind appliances, it is especially important to be careful of pets and small children. Thus use of boric acid should be carefully thought out in advance with these things in mind, and removal when the purpose has been accomplished should be thorough. In addition, the removal techniques suggested above are only for small uses, such as household application. For scenarios involving large spills, consult a manufacturer’s safety data sheet (MSDS) for boric acid.