Attics and basements are likely places for family memorabilia to accumulate. Neither location is a good choice.

Even if you have switched to digital photography and have scanned scrapbook material to your computer, you probably have family and professional mementoes that require special treatment.

Photographs, photo negatives, color slides, letters, news clippings and similar items deteriorate most rapidly when exposed to fluctuations in temperature and humidity, archivists and conservators say.

Basements and attics usually offer the extremes in temperatures and most likely are damp and musty.

For the family member determined to keep original records to pass on to other generations, a few tips might help to preserve important documents and images.

Scrapbooks are the most usual method of organizing paper and photographic mementoes.

Not all scrapbooks are alike, however, and the differences are important to note.

For those interested in long-term preservation, the scrapbook from a company dealing in archival-quality products is the right choice.

These scrapbooks are more expensive than those on sale at the local discount stores; but they offer a safer harbor for precious keepsakes.

How precious are the keepsakes? How replaceable are they?

Before some decisions are made about protecting family photos and papers, those questions should be asked.

Materials important for sentimental reasons but having no real value might not warrant the most expensive trappings.

In brief, here are some tips to guide the family collector and organizer.

First, here are some things to avoid:

Don’t get an album with the &uot;magnetic&uot; pages, that is, with adhesive coated pages and plastic covers.

Do not use cellophane tape.

Do not use white glue or rubber cement.

Do not write on objects with ballpoint pens.

Do not type on photos or paper objects.

Do not attach paper clips or rubber bands.

Have a plan. Rarely can a family member put together a scrapbook in one day.

Have a safe place to store the materials between the times you work on the scrapbook.

Shoe boxes and wooden drawers are not safe havens for cherished old photos and paper materials.

Enamel-covered steel boxes or file drawers are better choices.

Here is a short to-do list:

Order acid-free boxes and acid-free tissue from a company such as Light Impressions, 439 Monroe Ave., Rochester, N.Y. 14607.

Use white paste if you want to attach something to the scrapbook page. It’s water soluble.

Handle materials as infrequently as possible, especially those things of substantial value.

Invest in a pair of lint-free white cotton gloves to wear when handling your valuable artifacts. Fingers can transfer damaging sulphur onto the materials.

Consider making photocopies of materials in fragile condition.

Some special advice about photographic negatives and color slides is in order, as more families find value in the old images in today’s digital-directed scene.

If a collection includes negatives made between 1890 and 1950, it probably includes nitrate-based negatives.

It’s important to separate these from other types of negatives and other materials in general because of the harmful gases they emit.

How does one tell the nitrate from other negatives?

Sometimes the film manufacturer wrote either &uot;nitrate&uot; or &uot;safety&uot; on the edge of the film.

If not, however, here are some clues to nitrate film based on how it deteriorates.

First sign of deterioration is an amber discoloration of the film base, accompanied by slight fading of the image.

Next, the emulsion may become sticky, causing negatives actually to adhere to one another; a slight acidic odor may be noticeable.

Third, the film begins to show bubbles and to emit a strong, noxious odor.

Next, the film becomes soft and tightly sticks to the film next to it and may have a viscous froth on it.

In the final stage, nitrate film will degenerate almost entirely into a brownish, acrid powder.

Nitrate film can be dangerous. Keeping it as cool and dry as possible is more important if any deterioration has begun.

All photographic negatives should have special housing, beginning with the envelope in which each is placed.

Again, using acid-free materials is important, and a company such as Light Impressions is a source for the materials as well as information.

The same is true for delicate color slides, which should not be placed in polyvinyl plastic slide pages.

Slides may be stored in pocketed pages made of polyester, polypropylene, polyethylene or triacetate.

Photographs and slides are especially sensitive to light.

Fine original prints should not be hung on the wall for display. Rather, have copy prints made to use for show.

Photographs should not be hung on outside walls or in bathrooms because of the threat of moisture.

Heat from vents, fireplaces and other sources can damage photo and paper objects. So can dust and other air pollutants.

In other words, one should be aware of all the potentially damaging conditions in a normal home and be ready to protect the really valuable materials from those threats.