Apologies, I was hibernating (for like 12months)
Bigfoot, not sure where you're based, but I'm in Leicester and brought the dry ice from a company called dioxice / clean surface who are in troon ind est in Leicester. I want to say it was about 15-20 quid for 20kg of ice and another fiver for the box (which you can reuse as a "swamp cooler" for bbq's or if you need more ice!
I was stripping a swb Quattro and an e36 BMW, both have old tar but not as old as your car, and I did most with the first box and the small bits with an additional 5-10kg
First get some decent gloves - rubber thick ones from screwfix work well. I wore wolly ones underneath too but it was about -2 when I did it anyway!
Also wear a jumper so your arms are covered
I tipped 1/2 into the footwell of the car, left it for 5-10mins and then shovelled it across into the other footwell and gave the first a whack with a rubber mallet.. It literally came off in one frozen sheet which I put in the bin
5-10mins later, same again - shovelled it into the rear footwell, whack, remove..
I managed to get the 4 floor areas done but the last one took 10-15mins - you really start to loose the potency as it evaporates..
Onto the 2nd half, and I did the rear under seat area, rear parcel shelf and the rear wheel arches, then shovelled the whole bloody lot into the spare wheel well and left for about 25mins while I had some lunch, whack, remove..
Couple of things I learned -
Work fast; make sure the ice is doing stuff first then remove what you froze because it looses its mojo quite fast
Dry ice is FRICKIN COLD! if you use a dustpan to do the shovelling the rubber strip on the front will be destroyed in 5mins!
Dry ice is frickin cold but doesn't take much energy to evaporate it and it doesn't have much penetrating power - if you put it in a bin bag to keep it neat and tidy it wont do anything! Just makes the bag a bit cold and frosty..
Dry ice is dry - it doesn't stick to you so you can shovel with your hands
Dry ice is dry and it goes from ice to gas (co2) so work outside where there's ventilation, and there should be no wet muck to clear up after
So round 2 - the techie bit!
I had sound deadening to remove on vertical faces - trans tunnel, heel boards wheel arches, kick panels, etc and my initial plan of using "ice packs" made from bin bags was a no go.. Even cheap bin bags are thick enough to insulate too much..
What I did was make loads of "fences" from cardboard stuck to the shell with duck tape. This gave me a space to fill with ice to hold the ice against the tar directly and stop it spilling out everywhere. I actually experimented using an old shelf and some "stuff" but it just didn't work.. Do some oragami and it will work much better!
So again, shove ice in there, leave 5-10mins, remove and move on.. Then whack and remove
I found doing small areas worked best then shift the dry ice and make a new fence where you just froze (ie alternating from one side to the other of the trans tunnel).
Couple of other things..
- you can hear the tar pinging and cracking as it freezes and releases, once its been doing that for a min or two move the ice - don't waste the power! Once it releases move on!
- dioxice do contract dry ice blasting, they will also rent out their blasting room for about £50 an hour all in.. I did a set of split rims and a whole engine worth of components in an hour, awesome value
Hth - will add some pics tomorrow when I'm back af a computer rather than using a stupid phone