Stencil Spread

I am using some 5x7 fake skin from Amazon. It’s 3mm and I can tattoo on both sides without any issues. My issue is when I apply the stencil when I try to do some flash sheet practice the lines of the stencil tend to expand like a blown out tattoo. Any advice on how to prevent this? I usually let the stencil sit on the fake skin for like 10 hours and then alcohol some away. The deep blue look stays on the skin more than I would prefer. Should I shorten how long I let the stencil sit on the fake skin to prevent line detail from spreading. This is causing an issue more so when I practice 3RL and 5RL.