Here is my helpful gadget in my sewing room - a spray bottle of Krud Kutter. If you have ever used those dissappearing purple ink pens that become invisible in 48-72 hours, and then not gotten to your work before they are gone.....well this stuff is what you need.
Before I start sounding like an infomercial, you should know that my house is nearly 180 years old and my husband and I do nearly all the maintenece ourselves. So the house is full of many bottles of weird things and this one actually works like it says on the label - Plus I discovered that it also makes vanished purple dissappearing ink re-appear!
One day I couldn't find the cotton balls to clean gummy stuff off my sewing machine needle, so hastily I grabbed for the spray bottle and the overspray hit an item that had been marked but gone. Right before my eyes it was there again.
This saved my life since I didn't want to have to call the gal back in for another fitting.
The key here is that it goes bright purple again for only a couple minutes....then fades again quickly invisible. So, it is necessary to b prepared to re-mark with pins or something.
I bet this is common knowledge, but I felt like such a budding scientist when I made the discovery a couple years ago I went running up to Damman Hardware where I purchased the product to rave about it to them. They seemed unimpressed. Hopefully my news will be more useful to you than him. Joy