I answered a very similar question about the colour of wet paper in February (talk about getting old fast!!!) you can read it at:

http://www.last-word.com/content_handling/show_tree/tree_id/2580.html

Some of what I said was along these lines:

This is a very general effect in compound substances such as paper, wood, biological tissues, and ground or fibre glass, where there is a mix of materials that refract light differently. The light gets scattered so much as to ruin any clear image. The air in paper has a lower refractive index than the fibres, but if you can replace it with something that matches the refractive index of the fibres, the light can pass straight through, making the whole mass transparent or at least translucent, if the match is goodish, but imperfect. We call such a process impregnation.  Suitable oils work well, as long as the paper is nicely homogeneous, and you can remove nearly all the air.

In fact, years ago, when glass was very expensive, oiled paper or parchment was sometimes used for window panes. A primary school teacher of mine who had visited Japan, told us that paper walls were widely used in some areas, at that time, and that the foreigners were great objects of curiosity, but the Japanese did not wish to stare openly. They would go indoors, and wet paper walls in spots to provide peepholes. The dark spots were visible from outside however, so that the party was treated to a sense of being watched wherever they went in such an area. 

In some ways wood behaves similarly. A piece of dry teak or mahogany has a dull and whitish cast, even if carefully sanded, but if you treat it with a good transparent oil that soaks in to replace the air in the wood fibres, the light can go in deep, not getting out again before it has passed through a lot of the wood's pigment, so that it comes out a nice, rich brown, and shows the handsome patterns of the different colours in the wood.  .  . 

Right? Much of that applies to blonde hair too. It is not a true white, and light that passes through its mass shows the colour more intensely than light that bounces around its outside.

I hope that helps. Try reading the original, then call again if you are left in doubt.