EARLY MAN was no fool. He knew you did not make a fire by rubbing together a candle and a piece of wood. The candle was for waxing down his skis. The wood was for clubbing his enemies.

Industry, however, is proving early man was all wet.

One of the big sellers this winter in area drug stores, discount houses, supermarkets and houseware stores was a fireplace log not far removed from the candle-wood hypothesis. Sold under many names (Duraflame, Goldflame, Pine Mountain and Sterno, to name a few), this ersatz firewood is, in most cases, in fact made of compressed wood chips (one company uses peanut husks) and a crude form of paraffin.

The great advantage of the artificial log, which sells for around $1 for 3 1/2-, 5-and 6-pound pieces, is that it lights up in no time, doesn't shed bark and sawdust all over the living-room carpet, and doesn't make cozy nesting for rats. Plus it gives the user about three hours of fun watching copper salts or ammonium chloride burn in different colors.

Sounds too good to be true, you say. Take a look at the label on one of these logs and you also will find warnings reading:

Do not burn in a barbecue, free-standing fireplace or wood stove.

Do not use for cooking.

Burn log on a supporting grate.

Use only one log at a time.

Never add a log to an existing fire.

Never add any other item to a fire containing one of these logs.

Never attempt to move or break up a log after lighting. Use of fire tongs or poker could be hazardous.

Fireplace lovers who fail to heed this considerable list could be asking for trouble. While the National Bureau of Standards, which tested the logs for the Consumer Product Safety Commission, reports they are "perfectly safe" if used according to manufacturers' instructions, the manufacturers freely admit they can otherwise pose a hazard to health and safety.

Manufacturers are concerned, for instance, that more than one artificial "wood/wax" log burning at once in a wood stove could damage the stove.

"The heat that they generate is comparable to about three pieces of hard-wood," said Bill Lehmberg, manager of the specialty products division of Gold Kist, Inc., in Atlanta, which makes Goldflame logs. Most such logs, say the makers, give out between 80,000-90,000 BTUs. "The quality of many of the stoves is not that good. For insurance reasons, we ask that they [artificial logs] not be used."

Bob Ng, brand assistant on Duraflame for Kingsford Charcoal (which is a division of the Clorox Co.) in California, also said, "The main reason we do not at this time recommend this is that there is a wide range in quality in the free-standing fireplaces. In some of the poorer quality stoves, the heat from the Duraflame is enough to possibly damage the stove."

"Only a good ceramic fireplace could hold that much heat," said Lowell E. Wills, assistant gerneral manager of Great Lakes Consumer Products, a division of Great Lakes Carbon Corp., in Chicago and producer of the Pine Mountain brand. Great Lakes had been making the logs for nearly 10 years, Wills said.

Manufacturers recommend against using the logs for cooking -- or even marshmallow roasts -- because they are not sure of the toxicity level in coloring agents (mainly copper sulfate) added to the logs to make them give off pretty colors.

"There are chemicals in there and they are given out during use," Ng said. "We're not sure about the level of toxicity. We buy materials from a number of manufacturers.... The types of things we're using have not been documented to that extent."

"The color chemical that's in there might be toxic," said Lehmberg. "It woundn't kill anybody, but it would not enhance the flavor of what you're cooking.... It could make you a little sick."

"To determine toxicity is a very lengthy laboratory procedure," Wills said. "We haven't pursued that."

Wills believes many customers are using the artificial logs to start hardwood fires. But they should, in fact, be used alone.

"We do not encourage burning with cordwood," said Ng. "What happens is the Duraflame is designed to burn by itself at a certain speed. It tends to break up. As it breaks up, a new surface area is exposed to fire. Cordwood has a tendency to fall or pop or move around a lot. It can cause the Duraflame log to burn faster than it's supposed to and create a fire hazard."

Most logs are made of about 50 percent "slack wax," an unrefined form of paraffin, said Lehmberg. Manufacturers of the widely distributed name brands say they have no problems with the wax they have no problems with the wax dripping out, forming flammable pools.

"Some of our lower quality competitors do," said Ng. "There are a lot of regional brands."

Also, he said, "there are a lot of contract packers," whose products "other people put their names on."

Safeway and Giant are two such local distributors who put their names on logs made by other companies.

(The Safeway product is made by DG Shelter Products in Sacramento, Calif., a millworks that distributes nationally under its own name, DG Firelog, and others and in "direct competition" with Safeway. Shelter Products has been making logs for about six years, said operations manager Art Gardener.)

Manufacturers advise against poking artificial logs with fireplace tools or moving them around. "Wax can stick to the poker," said Lehmberg. "It might bring a live burning coal into the living room."

This, says Charles Jacobson, compliance officer in regulatory management for the Consumer Product Safety Commission (CPSC), is "the main complaint that we've gotten" about the artificial logs. The CPSC has already banned other types of artificial logs -- the ones used as decorative pieces over gas jets. The CPSC ruled they contained possibly harmful levels of asbestos and posed a waste removal problem, said CPSC spokesman Randy Hill.

Jacobson says he does not see any similar problems with the wax/wood logs.

"Most of these precautions are because of overly cautious insurance people," who would rather avoid any product liability problems from "multi-million" sales, Lehmberg said.

Ng says Duraflame is "currently testing with various models of stoves on the market to establish standards," perhaps resulting in labels on stoves that can use the logs. He estimates total industry sales in the Baltimore-Washington area this winter at about 1.8 million units. Several K-Mart and Dart Drug stores in the area had sold out last week and planned no more shipments before the next heating season. One Dart Drug store in Falls Church had sold "in the neighborhood" of 10,000.

If you plan to be among those statistics, manufacturers ask that you "read the directions carefully."