Here is an excerpt from an article written by Dorothy Leonard for Harvard Business Review and the HBR Blog Network. To read the complete article, check out the wealth of free resources, obtain subscription information, and receive HBR email alerts, please click here.

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Asked if he would be willing to share his hard-earned knowledge with others in the company before he retired, the engineer laughed. “Why would I do that?” he asked. “First off, I don’t owe this company anything more. I’ve given 35 years to this outfit, and I hope they miss me when I’m gone. Or,” he added with a bit of a twinkle, “hire me back at double pay as a consultant.”

There we had it in one concise capsule: a few of the reasons why retirees refuse to share their experience-based, business-critical knowledge — what we call deep smarts. By definition, those deep smarts are still valuable to the organization and underlie future as well as current success. They may be technical, as in the engineering example, but they can also be managerial, as when an experienced manager has hard-earned skills in problem identification and solution, crucial relationships with customers, or a detailed understanding of how to innovate.

If such knowledge leaves with retirees, it may be lost for good. In our research on knowledge transfer, we have seen companies greatly disadvantaged, if not crippled, by knowledge loss. Certainly, some expert knowledge may be outdated or irrelevant by the time its possessors are eligible for retirement, but not the skills, know-how, and capabilities that underlie critical operations — both routine and innovative. Organizations cannot afford to lose these deep smarts.

Lack of time or resources can, of course, constrain knowledge transfer. But one barrier to passing deep smarts along to the next generation that is often unaddressed is the expert’s inclination to hoard knowledge. Financial incentives, personal ego, and discontent or frustration with the company are three of the top reasons individuals choose to keep their expertise to themselves. But they’re also three issues that managers can actually change.

Let’s start with financial incentives. Many companies hire retirees back to do the same jobs they have always done but with double pay: consulting income tacked on to their pension. In the survey we conducted as part of our research for Critical Knowledge Transfer: Tools for Managing Your company’s Deep Smarts, 42% of respondents reported that kind of revolving door was a typical way of retaining knowledge. The moment that the time limit restricting rehiring retirees expires, the retiree clips his ID badge back on — and heads for the same door he’s been walking through for decades, again with little or no incentive for mentoring successors.

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Here is a direct link to the complete article.

Dorothy Leonard is the William J. Abernathy Professor of Business Administration Emerita at Harvard Business School and chief adviser of the consulting firm Leonard-Barton Group. She is the author or coauthor of four Harvard Business Review Press books, including aforementioned Critical Knowledge Transfer (2015).

Here is a link to my interview of her.