Effect of sunlight on natural shade paper

[pacificiam]

Hi.

I am working as Trainee in printing press. QA person from this firm fighting with purchase department abt shade variation in Natural shade paper.

Bt purchase department telling him dat this is happen due to effect of sunlight.

Due to shade variation LAB value of paper change. Bt its find dat L* value remain constant.

When we ask to purchase department abt it. They told us Sunlight never affect on L* value of natural shade paper. It only affect on a* and b*. Coz its only made up of natural material.

IS it true?

[mkulengosky]

You might want to define what you mean by 'Natural shade paper'. Are you talking about a specific substrate?

Also, are you trying to diagnose the effects of direct sunlight on the substrate itself?

Shift in L*a*b* values over a specific time period because of direct exposure to sunlight?

[maynardsayswhat]

Sunlight will alter the reflective color of just about any unprotected paper substrate if you let it sit there long enough. Don't leave your paper out!

If this is for an outdoor application, there are far better substrates than paper for long-term outdoor banners, signage, etc. Choose the right tool for the purpose.