CHICAGO (AP) — A Chicago conservator has restored the state of Illinois’ rare copy of the 13th Amendment signed by President Lincoln.

The almost 147-year-old document signifying the end of slavery is made of animal skin, which was creased and wrinkled, and some of the original iron gall ink had flaked away.

That made it too fragile to display, and it’s been stored in a vault at the Abraham Lincoln Presidential Library and Museum in Springfield.

Graphic Conservation Co. restored the document at no charge to the state, and will turn it over to museum officials on Thursday.

It will go on display in February.

Illinois’ document is one of at least 14 duplicate copies of the 13th Amendment signed by Lincoln. It also was signed by most lawmakers who voted for it.

Copyright 2011 The Associated Press.