If you want to keep the unions away from your doorstep, the National Association of Manufacturers has some advice: Make sure your employees are well treated.

But if all else fails, the NAM also has some more blunt suggestions to help their members keep their companies "union free."

In a new revised and expanded edition of its manual on how to keep unions at bay, the association deals with everything from the early warning signs of discontent on the shop floor to a list of arguments to persuade employees to vote against union representation.

Its major message is that unions are bad for business and bad for workers, but another more subtle message is equally clear: Companies that attract unions deserve them.

The manual, titled "Remaining Union-Free, A Supervisor's Guide," insists the organization is not anti-union. Instead, it says in its introduction, it merely wants to show how a union can hinder a company's growth.

"Many managers and employees fully understand how a union can hinder a company's goals of achieving maximum productivity, maintaining profits and rewarding the individual initiative of all workers, from the first-year worker to the chairman of the board," states the NAM, whose members remain the most highly unionized segment of the American work force. "But some employees may not understand how one of the major union-free benefits -- flexibility -- allows a company and its employees to reach their goals."

Unions, the manual states, "restrict flexibility and slow down vital market reaction time." It warns that unions force an employer to go to the bargaining table when the company wants to make changes in its operations. "Bargaining reduces the company's ability to react to changes in the marketplace," the manual warns.

Using chapter headings such as "Early Symptoms" and "When Things Get Serious," the manual is chock-full of tips for lower-level supervisors to help fend off union attacks.

Under the heading "Do's and Don'ts for Supervisors," the manual tells management officials to keep union organizers off company property, to inform employees of the benefits they currently enjoy, to warn people of the disadvantages of joining a union, to give their views of unions and union leaders, but to "campaign against a union seeking to represent the employees."

The manual also warns supervisors that it is illegal to attend union meetings, punish anyone for union activity or promise certain benefits if they reject the union.

In the "Early Symptoms" chapter, supervisors are told to look for "concerted activity" on the shop floor. "Concerted activity means two or more employees acting together and applies to union and union-free employees alike," the manual warns.

And while the law guarantees the right of self-organizing, employees who engage in such activity, the manual states, are not fully protected by the law.

For example, the manual reminds nonunion companies that, if a group of employees says it is dissatisfied with its pay, hours or working conditions and goes on strike to support its demands, the group's members cannot be terminated or disciplined. But they can be replaced.

In its forward, which warns that the material is "a confidential document for use by supervisory personnel only," the manual states that it is meant to assist supervisors in promoting "sound employee relations" so there will be no need for a union. It is through managers and supervisors that "the company's policy of maintaining a pro-employee rather than an anti-union atmosphere must be communicated and practiced."

To help arm managers and supervisors with arguments against unions, the manual contains statistics showing the decline in union membership as a percentage of the American work force over the last decade. In 1978, union members made up 23 percent of the work force. By the end of the 1980s, that number had dropped to 16.4 percent. Immediately after World War II, union members represented 36 percent of the nation's work force.

To keep unions out, supervisors are urged to treat workers with dignity, apply all policies fairly and maintain open communications with employees.

But a survey of employees' ranking of concerns matched by the guesses of supervisors as to how employees would rank issues shows there's still a lot of work to be done. While employees listed "full appreciation of work done" as a primary concern, supervisors listed it near the bottom of expected employee concerns. And "feeling 'in' on things" was the second highest concern of employees, but dead last on a list of 10 among supervisors surveyed. Supervisors guessed that employees would list pay and job security as their top two concerns.