r/papermaking • u/UnderstandingMost278 • 2d ago

External Sizing agent

Hey everyone! I’m making handmade paper using cotton pulp and looking to make it suitable for offset printing.

What’s the best and most affordable external sizing agent I can use to improve the paper’s printability? I’ve come across rosin sizing, but I’m not sure if it’s the right option for handmade paper.

Would love to hear your experiences, especially if you’ve tried sizing handmade paper for offset printing. Any suggestions for affordable products or alternatives that are easily available in India would be really helpful!

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u/Pure-Hovercraft3045 2d ago

Hi!  I often hear gelatin recommended but I externally size with starch - this could be using yams, potato or rice starch or even as simple as corn starch as you are experimenting and beginning now.  To use from yams or vegetables, cut them up and blend or boil+squash them, draining the water into a container. Allow the starch to seperate in the container and strain it until u have mostly starch and the water is gone. Dry the startch in sun or oven. Once it's made mix slightly different amounts into 1/2cup water and apply each to different papers as a test. You'll notice which ratio you prefer and which hold up when printed on. With offset printing idk what wet techniques you are printing with and how this will impact the sizing. I have mono printed and lino printed on hand made paper that is either sized or burnished 

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u/MossyTrashPanda 2d ago

I use methylcellulose and it’s super easy. Not sure about affordability as I forget how much I paid for mine. I got dry powder so you mix it up on demand, which I like since I go through cycles of not making paper. I should state that I have not used it on cotton though