i use liquid mask all the time. i brush it on. do 3 even coats. usually light. i do it like this apply one coat then let dry overnight then apply 2nd coat in morning. then when i get home from work apply 3rd coat. let dry till the next night and your ready to paint. or you can apply 1 coat and use a heat gun or hair dryer till dry. then do the same for coat 2 and 3.
when painting i always paint my black first. so i cut out all the black problem is this make it very hard to see your design that you have drawn out. so what i did is went to home depot and got some blue painters tape they make 2 type i use the one with the orange band it's low tack and wont pull up the liquid mask I cut all the black out and peel it out then i tape off the design. paint the black then peel the blue tape out. then i cut out the next design and paint that and so on.
here is a example of my work.
for this body i cut all the black out did the blue tape thing. paint the black. then i cut out the flame design and painted the candy red backed it with silver. then i cut the orange stripe and other orange out painted it. then i peeled the flame design out did the flu yellow fade then peeled all the whit out and painted it. then only stickers on this body are the charger, headlights and grill the rest is all hand cut.
for that i scanned the sponsors decal in the computer. once ther you can view the and paint them out. when you print them out select the properties button got basics and selct mirror image. this prints them out backwards. then i tap the printout where i want it with the image towards the body. and cut it out in the liquid mask. i also do this with the paint mask designs. it take about 3-4 hours to paint a body like this one.
hope this helps