My wife and I were married a little while ago and have a picture with some guest names in it hanging in our house. The ink in the picture is fading and I assume it's from the sunlight, but it receives no direct light at all, but still the ink it fading in some places. We thought we could retrace the names if we had a pen with ink that didn't fade. Does anyone have any thoughts? I've searched around and haven't found any black ink pens like this yet.