Find Non-Sticky Water-Resistant Wax for Sealing Letters

[homechemist]

I need to find out this kind of wax:

-it's solid hard in room temperature (it needs a knife to be cut), but also brittle
-it's melting in above 100C (212F) when heated
-it doesn't have sticky surface
-it needs to be water-resistant

So mainly this would be for sealing wax that can be used for sealing letters.
I think beewax is too sticky and soft for this.

 

[chemisttree]

You should look at highly crystalline paraffin wax. The craft stores have these in the candlemaking supplies.

 

[Borek]

I wonder if paraffin wax will not leave greasy stains on the paper.

 

[chemisttree]

I wonder if paraffin wax will not leave greasy stains on the paper.

Good point. A highly crystalline wax would minimize that. Softer waxes of lower crystallinity would definitely leave those stains.

 

[Borek]

Other question is, if the paraffin will stick hard enough to the paper. I have just rememberd - I have tried to seal letters with candle paraffin as a kid, and paraffin was easily separating from the paper. My bet is that being highly crystalline will make affinity even lower.

 

[chemisttree]

Paper is porous. The molten wax will penetrate the paper somewhat. Peel strength or the energy to delaminate the paper from the hardened wax is a more complex phenomenon. Usually the addition of a low modulus material like beeswax will help with that. Compounds like rosin are often added in pressure sensitive adhesives to increase peel strength, for example. It has to do with the rheology of the deforming adhesive at the crack tip...

 

[turbo]

The OP got me curious, so I Googled "how to make sealing wax" and found this page of formulas.
http://www.codesmiths.com/shed/workshop/recipes/sealingwax.htm

 

[homechemist]

Thank you for answers.
I have to also mentions that I would use this also for sealing food related stuff (like bottles, jars), so it's better if wax (+additives) will be natural and non-poisonous.

It's also important that wax is solid, but brittle in room temparature, so wax seal can be broken easily without any solvents.

Resin and shellac are hard solid materials in room temperature. If I add them to beeswax, it will become harder as wax. I'm just concerned about because shellac is flammable.

Also I'm wondering if this sealing wax will leave stains to paper or bottles.