Bind the edges of the screen with tape to keep it from snagging the garment. If the garments have noticeable stains, the best thing to do is to consult a textile conservator. Horror stories abound about people who, unaware of the fugitive nature of certain dyes, attempted to wash printed cotton dresses in water and detergent and ruined them as a result. Dry cleaning also is dangerous for it applies considerable strain to the fabric and seams and can dissolve some fabrics and trims such as early cellulose-based sequins. Keep steaming and ironing to a minimum or refrain from doing it altogether.
Heat accelerates the deterioration of textiles.
Ironing also applies physical pressure to the structure and thus is harmful to the item. Inspect costume items for insects and mildew. If anything is discovered, isolate the items in a sealed container immediately. Examine nearby items for possible infestation. If mildew is found, consult a conservator for the best cleaning advise.