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Abrasive Cleaning Prep
There’s no question that one of the quickest ways to strip old paint from a tractor is to sandblast the surface. The terms media blasting and abrasive blast cleaning more accurately define the process, since blast material can range from silica sand to ground walnut shells to dry ice to glass beads.
Besides the benefit of speed, abrasive cleaning can also clean tight and hard-to-reach areas that would be extremely difficult to get to with conventional cleaning methods. Of course, that can be a detrimental feature since air-driven sand has a way of getting into any and every opening.
Hence, one of the most important preparation steps is to go over the entire tractor, looking for holes that will let sand in and cause later damage. Examples include passages to the brakes in the pinion housings. Check, too, to see if any of the bolts you removed during disassembly left an open hole that will let sand into the clutch or shaft areas.
Before you do that, though, Jim Deardorff of Superior Coatings (a media blasting and painting company in Chillicothe, Missouri) insists that you remove as much grease as possible. Sandblasting, he says, will only drive grease particles into the surface. That is especially true if you use too much pressure that can pit or scratch the surface. If grease is driven into the pits or scratches, it will make it more difficult to apply a quality paint job.
Apply detergent and soak
Oe of his tried-and-true secrets is to use a hand sprayer to apply a coat of Dawn dishwashing detergent over the entire tractor. Let it soak overnight and wash it off with a power washer and hot water. It’s not that Deardorff specifically endorses Dawn; it’s the only detergent he has found that rinses clean without leaving any kind of film. Oven cleaner is a good alternative for use on extra heavy grease.
If you’re planning to blast the engine, you’ll need to give it a thorough inspection, as well. Cover any open holes and remove components that could be damaged, such as spark plug wires, a plastic distributor, coil caps, etc. Be sure to pull the good spark plugs and replace them with old plugs or dummies.
After that, anything that can’t be removed should be carefully masked. The same goes for any holes that can’t be plugged by other methods. Deardorff suggests first covering the part or opening with a layer of masking tape, which can be removed without leaving any residue. Cover that tape with one or more layers of duct tape, which can withstand the impact. On large areas, use a thick piece of cardboard or plastic with duct tape to seal the edges. That goes for the radiator, too, if it hasn’t been removed.
Finally, make sure you or the technician are using the right material for the job. While some tractor restorers say they’ll never use a sandblaster on sheet metal, others claim it is perfectly safe if you use a mild abrasive combined with low pressure and steady movement of the nozzle.
“Cleaning performance is determined by impact energy, which is based on the weight, shape, and hardness of the abrasive and the speed at which it impacts a surface,” Deardorff explains. “Consequently, abrasive blasting can be fine-tuned for a variety of cleaning operations.”