Matt,
You say Can but then say the 500ml or 1 litre which would indicate the liquid as opposed to the can? Have I read that right? Perhaps not?
I tend to use the spray on pens, simply because the sealer has two primary purposes, as a grain filler and as a sealer to prevent further liquids or solids from being absorbed. The filler element is best achieved by the fluid as the grain filler is the solids held in suspension in the sanding sealer. Generally with pens we are able to get a smooth enough finish not to need the grain filler element and thats why I use the aerosol. I believe that the aerosol preserves the colour of the wood better, for example a zebrano pen with rustins sanding sealer looks pretty naff compared to the aerosol.
