Sorry it's a little late in the day, I got sidetracked with all your orders, he he!!
I'd like to share two very different ways of masking, depending on the effect you would like to achieve.
The first method uses post-it notes. It's a quick and easy method if you want one stamped image to look as though it is behind another. It's a great way of creating a scene and makes the use of many stamps much more versatile.
First stamp the image that will be in the foreground of your scene onto a post-it note. I have used the Sheep celebrations 1 clear set.

Stamp the same image onto your cardstock, keeping in mind how much room you will need around it for the other elements you'll be stamping.

Trim around the image on the post-it and stick it onto the card stock, precisely over the your stamped image.

Stamp the image which you'd like to be behind the main image, over lapping the post-it .

When you peel off the post-it, here's how it looks

Using the same method I stamped the fence on the other side of the sheep. I also stamped some extra flowers and grass blades from the stamp set to complete the scene.
The second method of masking works very well with watercolours and is great if you want to create a flowing background wash behind your images without them being coloured.
You just need some masking fluid, available from any good art & crafts shop.

First stamp your image onto cardstock using a permanent inkpad. I've created a field full of sheep and flowers using the Sheep celebrations 1 clear set.

Before opening, shake the bottle of masking fluid well. The consistency should be liquid. If there are any thick bits, shake again.
Using either an old paint brush or a manicure stick, dip into the fluid and start filling the areas you wish to remain white. You don't need to put a thick layer of fluid on, just make sure there are no gaps.

Leave to dry (it should only take about 10 minutes). Here's how my card looks with all the parts that I wish to remain uncoloured, masked.

Paint your background wash over the entire card. You will see that the mask resists the watercolour.
I used several shades of green and yellow marvey le plume pens with water. If you wish to keep the edge of the card clean just stick down a couple of post it notes along the fold before colouring.

Leave to dry thoroughly.
It's so easy to remove the mask. Simply rub your finger or an eraser lightly over the masked areas and it peels away from the cardstock without any damage to the card at all. So your images are now left white for you to colour.


Note, it is important to ensure the masking fluid is completely dry before you begin colouring and that the watercolour is completely dry before you peel the mask away. Otherwise the cardstock will peel away with the mask and be damaged.
Another cool thing about the mask is that you don't have to mask your image to keep it white. You can stamp and colour your background first and add the mask and paint another colour on top.
Again, be sure that the colour and the mask are completely dry before moving to the next step.
