I asked this question( about water temp) to Mike Zikich the owner of Safe and Simple
http://www.safeandsimple.com/ ( he knows a little about removal) here is his response
Chris:
Both paperhangers are right, but I don't think they know why or when.
Water temperature can make a difference. Usually the hotter the better. The reason is that heat is transfered to the adhesive USUALLY causes the molecular structure to change. This action (in the case of wallcovering) is "stirring up" the atoms that hold the adhesive chemicals together.
So hot water ON THE ADHESIVE is better.
Hot water applied to the OUTER FACE is neglible.
Heat transfer through air or solids can vary on the enviroment (i.e. are fans blowing?) Depending on the wallcovering, using hot water can make a difference, but this is not true of all wallcoverings, examples:
Applying hot water to the outer face of grass cloth. It would make a difference because the porous surface of the grass cloth readily soaks up any water, thereby, the hot water is getting to the adhesive sooner.
Applying hot water to commercial vinyl does not really help. Since commercial vinyl is so think, by the time the heat transfers through the vinyl, it is (most likely) cooled to room temperature.
Applyin hot water to prepasted's helps. Since the paste was laminated to the back of the wallpaper at the factory, the heat transfer is gets to the adhesive a bit quicker.
Living in Southern CA, our tap water is never really that cold when compared to Canada on a hot summer day. There is probably a 30 degree difference. With that much temperature difference, it can make removal easier.
Keep in mind that by simply applying water (at any temperature) tends to make most wallpaper adhesive's properties change. The addition of heat can change the properties further. Our 603 product is engineered to chemically reactivate most adhesives that are made from natural sources. Clays, clears, are made of earthly or natural ingredients.
When you look at water or the above adhesives through a microscope you see what looks like a field stone pathway in your backyard. Different sized atoms, twigs, gaps, etc. Water or heat tends to swell the atoms causing them to want to move.
Enter VOV:
Just the opposite occurs when heat is applied to VOV. It actually gets stronger. VOV is man made. The molecular structure (under a micorscope) looks alot like window screen mesh. That atoms are aligned and in order. The adhesive is actually not thet great, but the fact that the atoms all line up is what give VOV it's sticking power.
When removing VOV it is best to wet it, then move the fluid around in a swirling manner. This swirling action is what disturbs the natural alignment of the atoms.
FYI: Have you ever noticed that removing wallpaper from an area that gets a tremendous amount of direct sunlight seems tougher? It is. The solar heat gain over a long period of time is continually cooking (and destroying) the chemical make up clay & clear adhesives. That is why it is nver a good a idea to paper inside window sills exposed to high temperature variations. In CA, a window sill can reach 100 - 130 degrees in the summer, but cool to 60 in the winter. That is a 100% +/- change in performance.
