When I first got my Surf, the chassis was SO clean it seemed silly not to take advantage of the fact and to try and keep it un-corroded through the English winters. I did this with the help of a mechanic friend so we had access to a proper workshop, you could do it without all this equipment but it would take a lot longer and it would be difficult to do a proper job.
The day before we did this job, the entire underside was steam cleaned and left to dry for 24 hours in a heated bay. If you underseal, you run the risk of trapping moisture, so it is very important to ensure it is clean and dry beforehand.
The actual spraying took about 1 hour.
I have taken a lot of time to ensure the information above is correct, but please remember vehicle manufacturers make alterations and design changes during the production run of a vehicle. No liability can be accepted for loss, damage or injury caused by any errors in, or omissions from, the information given above.
If you think any information is incorrect, confusing, misleading or incomplete, please feel free to contact me.