Dishwashers are death to a kitchen knife. Dull knives are far more dangerous than sharp ones. And most electricsharpeners make terrific doorstops.

So says Eric E. Weiss, knife sharpener and self-taught expert on knife history, safety, etiquette and lore.

Weiss sharpens knives for restaurants and caterers, and operates a booth at three weekly farmers' markets: North Berkeley on Thursdays, Berkeley Civic Center on Saturdays and El Cerrito Plaza the second and fourth Tuesday of each month. Weiss, 55, also teaches a quarterly class in knife sharpening at Paulding & Company in Emeryville. He lives in El Cerrito with his wife, Janet Jacobson.

I was born in England and grew up in northern Germany, mostly on military bases, from age 7. In that world, if a boy didn't have a knife by the age of 7, we thought something was really wrong with you.

I started sharpening knives when I was 5. By the age of 10, I was making money from it. My friends in the Scouts paid me 5 cents to sharpen their knives! But I never thought I would have a knife, scissors and gardening-tool sharpening business when I grew up.

I'm one of the few people who still do this by hand. I sharpen knives in two ways, one freehand and one with a jig that I've modified to suit my needs. A jig holds the knife like a clamp and it's attached to my table. It's like having a third hand, especially helpful with big knives.

I use four natural oil stones for sharpening: soft Arkansas, medium Arkansas, red Indian stone and ceramic. I also use six grades of industrial diamondstones, extra coarse to fine as a sharpening material. The diamond stones are 1 inch wide and embedded in plastic or a metal base. I work with these tools by hand, moving in an overlapping "Z" pattern. Pure elbow grease.

I do 35 to 45 knives a day, and 80 percent of them are kitchen knives. I charge by the condition of the knife, not by its size. Knives, scissors and garden tools generally run $8 to $10. I've sharpened machetes, swords, Samurai knives. Everything up to industrial tools and power saws.

Most people don't sharpen their knives at home, which is like never putting oil in your car's engine. Some work all the time and the last thing they want to do is sharpen a knife. And surprisingly, at least to me, a lot of people who are really good in the kitchen don't know how to sharpen their knife.

You should definitely be using a sharpening steel - the tool that comes with any knife set - every time you're done with your knife. Hold it straight up and down on your table. Start from the heel or the guard, depending on your knife, and draw it straight down at a 25-degree angle. Two or three times either side is all you need. More than that, you start removing your edge.

Dishwashers are my No. 1 nemesis. People seem to think that any knife can be put in a dishwasher. But in fact it's like sandblasting your car in order to clean it. The knife is banging against the basket, getting chips, nicks, dents, dings. And if the knife has any sort of quality steel to it, the dishwasher can remove the edge in two, three washings.

Some people think dull knives are better than sharp knives because they're safer. Wrong! You're pushing and exerting much more pressure on a dull knife. So when you finally break loose, in most cases, your fingers are in the way.

A sharp knife will give you a clean cut. Skin cut from a dull knife is essentially torn skin and takes longer to heal.

People ask me, "How complicated can it be, sharpening a knife?" As complicated as it is to build a good car! That's an exaggeration, but meaningful. Metallurgy has come so far just in the last 20 years that, compared to what used to be three, maybe four types of basic metals used, now there are 50-plus metals used for knives.

When I'm not sharpening, I'm reading about it. I have a substantial library about the history of knives and their manufacturers, and I subscribe to six periodicals. Some are point specific, like Tactical Knives, which is devoted to military, survival and hunting knives. Others are only about antique cutlery. Blade Magazine, the largest publication in the world for knives, covers the entire gamut.