Not recommend. There are two proper methods to coat a PCB.
- The first is via a conformal coating.
- The other is potting epoxy.
- Depending on your electronics casework, you may be able to fill with with non-conductive epoxy.
- You have to be concerned about any cabling.
- Once potted, your gear is unrepairable. You have to watch out for connectors.
- If they will with epoxy, they won’t work any longer.
- If the PCB is depending on cooling via the case, you can try heat-conducting, electrically insulating potting epoxy.