I know the old John Donne map store in Little Bourke St Melbourne used to sell a brush on (wax?) product for waterproofing paper maps (topos etc) called perhaps ‘Map Seal’ or the like. I admit I have never used it, or a spray on silicone normally designated for raincoats, boots etc (eg ‘Camp Dry’) which I know others sometimes use.
I have betimes laminated a paper map eg when traveling in Fiordland etc – but which makes them significantly heavier!) but for several years now I normally either forego a map, place it in a large snap-lock bag or use a phone app such as ‘Paper Maps‘ and downloaded topo maps such as Vicmaps.
I have posted about a DIY method of Waterproofing Tent Floors (and seam sealing) which is inexpensive and works well. I admit I had not thought to apply this method to waterproofing paper maps but I see that the redoubtable Tim Tinker has as this post DIY Waterproof Map illustrates – and clearly it works, so I recommend the method (and link) to you.
Here is a photo of a resultant waterproofed map which Tim has kindly allowed me to re-post as proof of concept. As Tim spends most winters ski touring and tipi camping in wilderness terrain this method clearly works.
An easy, bullet proof, method is to use clear spray rubber: Gorilla Glue or Flex Seal has in large spray cans app. $12/14 USD. Apply generously to one side, take tweezers and immediately relocate to dry (least it glue itself down around the edges). In a few hours repeat other side.
Note it also soaks into the paper. I printed off a map on standard copy paper, treated it, and wadded it up and threw into a bucket of water overnight- no penetration into the paper.
I tried spray urethane but maps become stiff over time and yellow and no where near the protection. The spray rubber also adds some tear resistance to the copy paper.
Thank you Jo. I presume you mean the Gorilla Glue Patch and Seal Spray? May not be available everywhere though. Cheers, Steve.