MITRA Forum Question Details

EditDeleteThis is really a two part question: what are the long-term aging properties of shellac and what are the long-term aging properties of sharpies. I would not worry about the former too much as shellac is commonly used as a surface finish for instruments and is also what the client appears to prefer (shellac is not recommended on paintings, works of art on paper, and other types of artworks). It may yellow/darken a bit but that will likely lend a nice aesthetic to the guitar. The sharpie is a bit more of a concern as the dyes used in these markers are not at all lightfast. Micron pens or other pigmented inks may be the way to go here as carbon black pigment(s) will always be more stable and lightfast than most organic and/or synthetic dyes. Also be aware of solubility no matter what you use....you probably want to end with a final spray coat as opposed to brushing but you can easily test this out on a test panel to make sure your black design does not smudge or dissolve away with the final application of shellac.

EditDeleteShellac will not eat away at carbon black. I promise :)

EditDeleteWell the least you can due is attempt to exercise due diligence....while not all manufacturers adhere to ASTM standards you can at least check to see if your chosen medium has an associated Lightfastness rating...you can read some about that in our "ASTM and Lightfastness" document in the Resources section. Honestly all shades of sharpie colors will fade....but perhaps one of our other moderators will be able to weigh in on other possible options. But you really will need to make sure your sharpie/micron pen design (whatever you choose) will not be bitten into by an alcohol-born shellac solution...mock-ups are key here. For the micro pens you may need to gently scuff the surface for the ink to "take"...again something you can figure out by doing a test.

EditDeleteThe colorants in Sharpies are predominantly dye-based, which means that they are most likely sensitive to light, although formulations have changed. (N.B. When a writing implement is advertised as "permanent" it means that a mark will not wash away in the laundry, not that it is permanent to light.) I suggest looking at the new nano-particulate pens. Inks formulated using pigments are generally more lightfast than those formulated using dyes. Some manufacturers do have light sensitivity information available. Theoretically the shellac should not interfere with pigmented inks.