Low-cost, portable shelving with a professional look

For the budget-conscious, here is a wall-hung arrangement of plain, unfinished pine shelves that is both practical and good-looking.

The whole assortment of 12-inch-wide pine shelves and brushed stainless steel brackets was bought at a local lumber store and installed by New Yorker Donald Kotter in the tiny office-study of a walk-up bachelor apartment.

Since the wall is 12 feet long, Mr. Kotter bought 12-foot-long lumber so shelves would have an unbroken, wall-to-wall fit. ''This gave them a customized look from the outset,'' he explains, ''even though everything about them was low-cost and standard and straight out of the lumberyard.''

He carted the shelves up the stairs himself. But some apartment dwellers, he cautions, might have a problem getting 12-foot-long shelves indoors, and would need to have them cut into two sections.

The only finish the designer gave the plain pine timbers was a light sanding and a coat of wax. To give unity and to carry the unfinished pine look around the room, he bought inexpensive shutters (at the same lumberyard) to place at the two windows in the small, sunny room. The table-desk, which appears to be part of the arrangement, is a Finnish classic. It could also be an inexpensive, do-it-yourself table made out of a flush door and set on 4-by-4-inch pine legs, or manufactured legs, all of which are available at lumber stores everywere.

The whole arrangement is portable. It can easily be moved or recut and rearranged to fit new spaces.

Why does this group of shelves look more professional than most homemade efforts? ''Composition is the key,'' Mr. Kotter explains. ''I didn't just put the shelves a foot apart and let it go at that. I considered carefully what I wanted each shelf to do and contain, and exactly how I wanted each to function.''

He placed the first shelf at table height. It holds a portable typewriter, pencils, dictionary, and other supplies that extend the usefulness of the table-desk, and it makes the two surfaces appear as one. Having placed the initial shelf, he sat at the desk and stood in front of the wall to determine where different things would be easiest to reach. Function can almost dictate the arrangement of shelves, he says, if you think through logically what you want, and where.

''I'm a magazine collector,'' he says, ''so I arranged stacks of four or five copies of older references on a higher shelf. I placed shallow stacks of current magazines on a lower level, with just five or six inches between shelves. Books require deeper space. I put one shelf at eye level for certain art objects and books, and a bottom one at what I call 'storage level,' where heavier boxes and a typewriter case can be placed without destroying the illusion of an uncluttered, artistic arrangement above.''

He terms this shelf a ''visual trick,'' because it is placed high enough to leave the floor free, yet defines itself as a place for putting big things out of the way. He places no shelf higher than he can reach, which means there is plenty of airiness left at the top of the room.

Once all the more practical determinations are made, he says, it's important to try the shelves in place and stand back across the room to see if the proportions please the eye; to get the ultimate effect, you must remember that ''composition is everything.''

Mr. Kotter, now a partner in the firm Design Multiples, chose architect's lamps to light the room because of their flexible arms and shades. One is turned up to create a soft, indirect light bounced off the ceiling. The other is pulled down over the table for work or study.