'Window blankets?'

We are interested in a way to keep the house heat from escaping through the windows after dark. Our needs would not be met by rigid shutters, and we have already investigated the idea of insulated shades attached to the widow frames. They are too costly for us to consider. However, we have heard of "widow blankets," which can be made at home, and wonder whether you might have some information on what patterns or materials are available to the do-it-yourselfer. Mr. and Mrs. D. E. Mix Park Forest, Ill.

You're probably talking about the Window Blanket Company in Lenoir city. Tenn., but the product is not something that can be made at home.

The Window Blanket comes in three shades -- white, rust, and tan -- and has a cotton facing, insulated lining called Roc- Lon, and polyester filling, which is similar to a sleeping bag. It looks very much like a drapery, is hung on a care rod, and comes in one standard size 45 by 84 inches.

"We do make custom lengths, however," explains Jake Smith, marketing director for the company, whose address is: Rout 1, PO Box 83, Lenoir City, Tenn. 37771. The phone number: (615) 986-2115.

The Window Blanket has been tested by Du Pont, according to Mr. Smith, and has an R-value of around 2.

A competing product called Window Quilt is made by the Appropriate Technology Corporation, PO Box 975, Brattleboro, Vt. 05301. There is also the High "R" Shade made by the Insulating Shade Company, 17 Water Street, Guilford, Conn. 06437. Other products are also on the market.

The cost may be far higher than you wish to pay. The Window Blanket costs $ 49.0 panel, or under $3 a square foot. The Window Quilt is $4.25 a square foot, but the R-value is higher.

I am not aware of the kind of low-cost product you are seeking.

Perhaps a pair of ordinary heavy drapes would do the job, but even standard ones can be very high-priced. You can, of course, make sure that there are no air leaks around the windows by caulkin g them thoroughly, but this will have to wait until spring