Hi! I don't know much about chemistry but was hoping that some of you guys could help me with a quick question. I build wooden model ships of sail as a hobby. One "trick" for giving sails and rope an aged look is to dip them in coffee or tea and let the tannin dye the materials. The problem is that these liquids are (of course) acidic. Some folks say this is a bad practice because, over time, the acid will cause the rope and sails to break down. Here's my question(s): Is there a safe and easy way to neutralize the coffee/tea? Will it be permanent? The reason I ask this is because in adjusting the pH in my aquarium hobbies, I have found the effect to not be permanent. Is there an easy way to calculate the resulting pH before making any adjustment? Thanks in advance for any help!