When I first started making customs I was using Krylon spray on sealant, bad idea
it made the pony sticky and that pony picked up every piece of dust and hair floating in the house
So what I did was I bought proper sealant (I use Folk Art Satin/Matte liquid sealant) and I applied that. It provided the right protection for the paint job while removing the stickiness of the other sealant.
I hope that helps