Using Barcode Fonts
One of the easiest ways of printing barcodes is to use barcode fonts. You just select the font in you application, like a word processor, and type the characters in the barcode. The code appears on the screen and will print out as part of the document. What could be simpler? The main problem is that your word processor will try to print the code no matter what point size type that you specify. However, the smaller the point size you use, the higher the resolution of your printer must be to render the code properly. If you have a font, such as Code 39 installed, try generating a code using a 10 point type and printing it on a 300dpi laser printer. Now look at the code under magnification. Compare the width of the narrow bars with the width of the narrow spaces. They should be equal. If you're printer is like mine you'll conclude that the bars are about twice as wide as the spaces. This would not be an acceptable code.
Barcode printing programs will prevent this problem from occurring. Most programs will not print a code unless a narrow bar is at least three dots wide. For example, on a 300dpi laser printer each dot is 0.0033 inches in diameter (1/300). Three dots would be 0.01 inch. So, I shouldn't print a code on a 300dpi printer with a small bar less than 0.01 inch wide. If I use fonts the printer will try to print any code I tell it to.
If you're going to use fonts then run some test samples. Print codes at various point sizes and look at them under magnification. Again, look at the narrow bars and narrow spaces. They should be equal width. Find the smallest point size that you can print in and still have them equal. The smallest point size I use with my 300dpi printer is 24 point. I have a freeware Code 39 font that I got from Shareware.com. Commercial sources for fonts include Azalea Software, Rivers Edge Corp. and Bizfonts.