10 ILCS 5/7-18
The primary ballot of each political party shall be separately printed upon paper of uniform quality, texture and size, but the primary ballot of no two political parties shall be of the same color or tint.
The election authority shall, at least 15 days prior to the date of the primary, post in a conspicuous place in his office an announcement of the color of the primary ballots of the respective parties, and, in the case of the general primary, shall also publish such announcement for at least 1 week in at least 2 newspapers of general circulation published in the county. In the case of the consolidated primary, the election authority shall publish such announcement at the same time and in the manner provided for notice of the consolidated primary in Section 7-15 of this Article.
10 ILCS 5/7-18