I'm starting painting my tips with the white polish nail, in soft light strokes. I apply 2 coats of white colour, but they don't have to be even.
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So using a old eye shadow make up brush with a round tip, I'm gonna dip it into the acetone, wipe it on to the paper towel, and with light strokes side to side, I start to remove the white paint that I want to get off to create the shape that I'm looking for.
Also, If Im going with the brush into the corners of the nails, I can clean them a little bit. This helps to remove the paint from my skin.
After the tips are completely dry, I apply one coat of the pink colour over the entire nail for a natural finish.
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And the last thing it's advisable to apply one more coat of clear polish for protection.
I have been using this method for my nails about 3 months, and now just takes me 15min!