I’ve used 3M Hi-Tack 76. It’s what CubCrafters use in the factory.
It creates a very stringy, tacky surface on both sides.
In my case the insulation was a fibre blanket with a vinyl backing.
When using Solvent based materials in confined spaces make sure you have good ventilation. Put a fan in the area and keep it on all the time, before, during and after. This will stop the build up of vapour.
Keep sources of ignition away (sparks, flame etc).
A carbon filter respirator is a good idea (air fed is even better, but not needed for shorter working times). If you smell or taste any solvent getting through the respirator, it is time to get a new one, as the activated carbon is exhausted (carbon has absorbed as much as it can).
I bought a tin of each – the one on the left is the tougher stuff but contains toluene
I think I might break from the Socata TB tradition and put some proper stuff on the firewall. Probably aluminium fronted
http://www.aircraftspruce.com/catalog/appages/soundex7.php?clickkey=325804
unless somebody wants to suggest something better?
Soundex worked well in the floor of my Mirage for thermal insulation.
Does anyone have some Soundex in the UK, about 15mm thickness?
I can get some from Spruce but it will be expensive to ship to the UK. The better way would be to get it shipped to the engine shop and get them to throw it in the engine box, but then I won’t have it while the engine is still out.
It appears that the Soundex which is firewall certified is not aluminium faced
I looks like the SX-600 is not much more expensive, but thicker. Notice the unit of measure is per foot, not one sheet.
Peter, it would be nice to take plenty of photos and report on this project. Insulation is one of my next projects I plan to do this year. Thank you!
The TB20 has two main foam areas:
The firewall foam lasts only a year or two. The rear bulkhead foam lasted about 14 years and now turns into powder when I touch it. Obviously it doesn’t get touched in normal ops because it is accessible only by climbing through the rear hatch but it still needs to be there because the luggage compartment gets extremely cold (below freezing) during flight.
For the firewall, I will probably buy the SX-500 and have it shipped to the US engine shop and then returned with the engine. The SX-600 would be better but I think it’s a bit too thick… It would get in the way. Any opinions?
While the engine is out I will cut out some cardboard templates for the firewall foam. I can then rent them out 
Cardboard cutouts done for the firewall foam
Getting MEK resistant gloves is non-trivial. Latex should work for a bit (googling for latex gloves does produce hours of entertainment, for those suitably inclined ) but all the options which actually work perfectly are very thick laminated gloves.
