For sealing primers I have used various colors of nail polish.
I would color code the brand of primers by using different colors of nail polish.
Red: Winchester
Blue: Remington
Green: Federal
Clear: CCI
Black: Black Powder Load
I did this for years without any problem. Any residue that was left after shooting went away when the gun was cleaned.
But what I found out is that if you clean your brass in a tumbler, and use good loading techniques you really don't need to seal reloads at all.
I am currently shooting up a batch of 38's and 357's that I loaded over 20 years ago. No primer sealing, and no problems at all.
I suppose if you were going into very harsh and wet areas it might be some help to seal the primers and bullets, but otherwise it isn't necessary.
One hint to sealing bullets, put a light ring of sealent (I used nail polish) around the inside of the case mouth AFTER charging the case, then seat the bullet. Carefully pick up the cartrige and set it base down in a tray for a while. This will give the sealent some to dry without being disturbed.
I believe Dillon sells a commercially made primer sealent, but I'm not positive.