I was faced with a similar problem of cleaning up pine beams and trusses in our old barn. I too, thought of getting blasting kit and doing the job myself, until I started looking at the protective gear that you need in order to survive the process. If the beams aren't in situ, then it would possibly be a whole lot easier.
The pros weren't that keen on the job as the roof had just been done and the felt was still exposed - they reckoned that one slip and I'd be looking at a big hole in the new felt! They suggested that once the ceiling was plasterboarded, they'd be able to do the job, but would still need to put ply over the plasterboard alongside the purlins. Ho hum. Of course, the job should've been done before the roof, but...... :roll:
In the end I bought a Festool Rotex sander and lots of 40 grit discs and did the job myself. Protective gear was just a Trend Airshield as I didn't fancy the muck on the beams (face masks are no use to me as I wear specs and they steam up). Hooked up to a Festool extractor the Rotex did the job really well, although it can't get tight into the corners of course. If I don't factor in the cost of my time then doing the job paid for the Rotex and then some, and it's going to be a very useful piece of kit; it's already produced a lovely finish on an old table top for her ladyship to French polish, so she's impressed too (bonus!)
I seriously considered the Festool Rustofix, which is a vicious wire brushing machine. I had a play with one at my nearest dealer, and it cleaned up some samples I took along in no time. However, the weight of the thing meant that I wouldn't be able to use it overhead, and when I tried their demo Rotex I knew that would do the job. I've still got a lot of old doors, boards etc that I can clean up in comfort, and the Rustofix is still tempting...... probably have to sell it after I'd finished, though, and I'm definitely not selling the Rotex!
