Clear coat over sharpie autograph?

It would be pretty easy to test this out. Draw with a sharpie on a piece of plastic and spray it.

I have almost 100 sharpie autographs going back 30 years and none have faded.  Most are on clothing (jerseys/hats) but one is on a boxcar, and others are on plastic.  It wouldn't hurt to cover with dullcoat. Fwiw I've even washed clothing items which have been autographed and none have faded.

Of course, I'm assuming none are stored in direct sunlight.

-Greg

Interesting thoughts.  I have a K-Line SP Daylight painted boxcar signed on one side by Maury Klein and Nick Ladd on the other.  It came to me well over 10 years ago out of a prominent TCA members collection and dates to the 90's.  I have never had any issue with the signature fading.  I often run it with my K-Line 21" daylight cars and call it my graffiti car. 

Clear coating could preserve the signature longer, however I would test it with a sharpie on something else first.  The last thing you would want is to have the signature run or be damaged by an incompatible clear coat.

I would also mention that autos can fade from indirect sun and light bulbs. I now keep my signed pics/baseballs in a drawer. Just be careful and check on it even if you clear coat it.

Definitely test compatibility, …..spray the first coat very lightly, if you see no adverse reaction, leave it alone for 10 minutes, and then recoat again, with a light coat, and allow to sit for another 10 minutes, if all is well,  do one more final medium wet coat to desired finish. Not too wet, or you’ll get lift up,….

Pat

First, to test it it would have to be the same plastic.   You could probably use the inside of the car.
Second,  use a model paint that is compatible with plastic.
Your fading seems to be the exception. Others are not reporting this in this thread.   Could this be a singular issue?  Some other factor at play?

Alan

If fading (from UV exposure) is a concern, you might try this product...

UV Clear Coat

...after testing its wet effects on Sharpie ink, as several above have mentioned.

I weathered and applied graffiti with multi colored permanent sharpies to two buildings in the past year. Both were sprayed with clear coat to seal in the weathering. For one building, which also had decals applied to it, I used two coats of a heavier amount of clear coat to seal it in, as I do with all decals. I definitely experienced some bleeding for the sharpie graffiti. It didn't kill my project, since I was weathering a run down building and was able to apply additional weathering where the sharpie graffiti bled, completely hiding the effect.  However, it did give me a little concern at the time. For the other building, which did not have water slide decals in need of sealing, I applied a lighter coat of clear coat (a simple one coat mist, followed by another after it had dried overnight). There was no noticeable bleeding of the sharpie on this one.

I agree with others about testing it. The key is what others have said, use a very, very light coat. The idea is basically that the paint is almost dry when it hits the surface, which means the solvent that keeps the actual clear coat liquid is almost all gone. Use  a very light coat and do it from a distance and see if on the sample it runs, practice it until it doesn't.  As they say, several light coats is better than one heavy one.

FWIW, the Sharpie is alcohol based, so any coating that has alcohol will likely affect the writing.

Why not purchase a nice, inexpensive display case to hold the boxcar? They can be had easily on Amazon and other sites.

I use Future floor wax to seal the decals on my car models.  It is water based and self leveling. It does not affect the black or silver Sharpie lines I use for trim on the models such as window gaskets and chrome.

Try using Transparent Aluminum to seal it in.   (Sorry couldn't resist!)

Even minimal exposure to lighting, either direct and indirect, can affect signed autographs.

If you use a display case, make sure it is marked as UV resistant.