Web Growth Question

[D_Max]

Web growth. Try'd googling that! We'll I did and found out the www is getting bigger alright!

I have a series of questions about web growth and would like to start out by asking it's
true down and dirty definition.

Carl

 

[heatset]

Re: Web Growth Question

Are you referring to the growth that occurs after the book is bound?

If so that is simply caused by the fact that the paper is absorbing moisture that is lost when the web goes through the oven.

 

[D_Max]

Re: Web Growth Question

Thanks for the reply.

Yes, that's what I'm refering to. How do you go about minimizing this phenomenon?

 

[heatset]

Re: Web Growth Question

The best way to minimize web growth (signature growth) is to run the lowest possible temperature in your ovens, while still drying the ink.

What is happening is the paper is absorbing moisture after the book is bound. The more heat you apply to the web during the drying process, the more moisture you are removing from the web.

The longer your ovens the lower you can run your web temps and still dry the ink. If you have good inks and 20 ft ovens you should be able to run your web temps between 200 - 210 degrees and still get a good set on the ink. Shorter ovens naturally require more heat to be applied, as the web is in the oven for a shorter period of time.

If you have short ovens you may have to slow the press down.

Signature growth is typically worse with uncoated stocks, but you can run lower temperatures on uncoated.

 

[jlind]

Re: Web Growth Question

That was an excellent answer by Heatset. One additional way to minimize the phenomenon is to build some schedule time into the process to let the paper grow before you bind it. Not a popular strategy when you needed it yesterday.
John Lind
Cranberry Township, Pa
724-776-4718