Q: Can you please give me some ideas for updating my spring-of-'84 linen duster. It's a self-striped beige fabric. The new spring fashions for 1985 appear to be totally duster-less. I.C. A: Your duster has not bit the dust. All you have to do is dust off your oversized blazer and wear it over your duster, as illustrated here. This look comes to you courtesy of Paris designers Marithe & Francois Girbaud, who feature it in their spring collection. If your blazer isn't a solid color, don't worry. The Girbauds also put a striped blazer over a checked duster, so don't be afraid to play pattern on pattern.
Q: Because leather items are so expensive in the stores, I'm ready to try my hand at sewing a leather skirt. Can you help me find leather skins? -- C.T.
A: The quality of leather skins offered by Iowa Pigskin Sales Co., Route 2, West Branch, Iowa 52358, is quite high, according to Rosalie Lemonstree, q) whose Fashion Sewing Journal features several pages of tips on sewing with leather. The average price is $3.60 a square foot. You can obtain a sample set of 15 suede and smooth-leather swatches for $2.50 by writing to Judy Antone in West Branch. If you want to know more about sewing with leather, write to Lemonstree at 320 East 54th St., New York, N.Y. 10022. Her newsletter costs $16.50 for one year.
Q: We will be going on a cruise to Acapulco in April, and I'm not sure how formal a "formal evening" aboard ship will be. Does that mean that I must wear a full-length gown and that my husband must wear a tuxedo? We have those things, but I don't want us to appear overdressed if most of the passengers are wearing less-formal dresses and suits.--M.N.
A: Julie Benson of Sitmar Cruises says that there are usually at least three formal nights during her company's 10-, 11- and 14-day cruises. Women wear anything from dressy pantsuits to long gowns, but cocktail dresses predominate. Many men wear tuxedos, Benson reports; others prefer a suit and tie. Men are requested to wear a jacket and tie in the dining room, except when casual evenings are designated.
Q: Can you please find a pants pattern with stretch-back waistband--not pull-on pants that stretch all the way around, but rather those that stretch in back only. I can no longer buy Ditto's pants. These had gathered stretch waistband insets over the hips, and they fit better than any pants that I've worn before or since. The stretch-back waistband is a good compromise. I wear a size 12-14.L.M.
A: Kwik-Sew Patterns No. 1129 (sizes 6, 8, 10 and 12) and No. 1130 (sizes 14, 16, 18 and 20) are straight-leg pants with elastic at back waist. The front has a regular waistband, pleats and a front zipper. If Kwik-Sew Patterns are not available at your local fabric shops, write to the company at 300 Sixth Ave. North, Minneapolis, Minn. 55401.
Q: What is the proper width for men's pant cuffs? --J.J.
A: Award-winning menswear designer Alan Flussr says that cuffs should be from 1-1/2 inches to 1-3/4 inches wide. "The use of the cuffs is optional," Flusser addds, "but they do add more weight and pull, thereby emphasizing the line of the trousers."
Marylou Luther welcomes questions for use in this column. She regrets she cannot answer mail personally. Send your questions to Clotheslines, Los Angeles Times, Times Mirror Square, Los Angeles 90053.