A new nib of a fountain pen should be cleaned from grease and factory-applied anti-corrosive lacquer before the ink will flow evenly. Some artists recommend sucking on a new nib to get it ready for ink. Manufacturers recommend immersing the nib in boiling water. An alternative is holding the nib briefly in the flame of a lighted match — but be careful — the heat can alter the temper of the nib.
Nibs must be kept clean during use or the ink will not flow freely. They should be wiped with a soft rag and afterwards washed and dried to prevent corrosion. The best way to clean lettering or drawing nibs is to scrub them gently with a wet toothbrush. Crusted pen nibs should be scraped or brushed clean before using. Use a scalpel or an X-acto knife. A fiberglass brush and a Swiss Army knife is also useful.
From nibs and brushes: Clean wet brushes with soap & water. Clean dried acrylic paint with acetone, denatured alcohol or equivalent product.
From clothing: While paint is wet, clean with water and/or window cleaner. Dried acrylic paint is permanent on fabric when applied to fountain pen nibs.