Paint Stripping?

[Quinnf]

Ok, some results to report.

Added about 1/2 bottle (that would be about 16 ozs [1 pound/454 g for you north of the 48th parallel] of "Crystal Drain Cleaner" from Home Depot to half a five gallon bucket (you're on your own with the arithmetic) of _really hot_ tap water.  Lots of angry boiling-type sounds came from the bottom of the bucket.  Stirred the stuff around until the angry noises subsided to keep from burning a hole in the bottom of the plastic bucket, then began carefully loading painted parts stripped of nuts/bolts/pins, etc.  First the cylinder head, then cam covers, manifolds, nuts/bolts, etc.   Then topped up with more really hot tap water until the liquid just covered the parts (probably 3/4 full) and stirred to distribute the stuff around.

The solution immediately turned black and boiled like a hot tub as carbon came off the parts.  Then it changed to a sort of blue-green black as the paint dissolved, then lightened somewhat as the gray primer and plaster filler came away.

I left the bucket in the laundry sink overnight and removed the parts early this morning before work.  Rinsed them with hot water and brushed the paint residue out of the grain of the cast iron and set the parts aside to dry.

Last engine I stripped, I spent about a month of afternoons with chemical stripper and flap sanding disks and a whole lot of elbow grease to get all the paint off. 

Regarding disposal, it occurred to me after I posted my last that this stuff is drain cleaner.  It's intended to be dumped down the drain and the municipal waste treatment evidently can handle small amounts of the caustic stuff.  The paint residue, which might contain lead, is settling in the bucket as I type.  I'll pour off the liquid this afternoon and transfer the paint residue to newspapers that the Hazmat folks can have next time they announce a pickup.

Quinn

[bitsnpieces1]

  Right on Quinnf.  You got it right.  Settling or straining to get the solids out and then treat them as a hazardous lead material is the way to go.  Dump the leftover used solution down the drain a little bit at a time followed by a good bit of water to flush it on down the line.  You don't really need to use hot water to dissolve the powder to start with, it'l make its own heat.  Part of what makes the powder work as a drain cleaner is that when you put it in the drain it generates a lot of heat to melt greases and oils. Makes it real bad to use in plastic piping since it tends to melt it.   
  You can also let some of the water evaporate to reduce the volume before dumping.  Metals tend to settle out in caustic solutions, it's acids that dissolve them.  If you are going to have a good bit of the waste liquid (say 5 gals or more) you ought to check with the sewer plant people, they would like to now when it's coming so they they can handle it.  They also might just tell you to bring it on by and they'll feed it through the plant for you.  Most plants tend to create acids during the biological process (same as most biological activity) and they need to find ways to conteract it.  We used to haul the caustic waste from the electric power plant to add to our plant as we needed it.  Saved us a WHOLE BUNCH of money on chemicals and the power plant on disposal.  We just needed to make sure it didn't have a bunch of toxins in it. 

[listerdiesel]

Couple of thoughts on the subject after doing a 'few' engines over the years:

We use a commercial paint stripping company at our factory, and anything that needs doing tends to get included with the factory stuff, so we get a reduced or nil cost :-))

The strippers use a variety of methods, the most environmentally friendly is to put them in a very large walk-in oven which runs overnight and reduces the paint to a fine powder/ash. There is no oxygen in the oven to speak of once the first bit has gone (it is an electric oven) so external fumes etc are minimal.

Once out and cooled off, the paint is gone with some slight surface marking but a brush over usually takes care of that.

The other method is wet stripping where they use a chemical to remove the paint. This is a little more involved, as the chemical will attack some metals and more importantly will attack cast iron if the solution is too strong or the parts are left in too long. The surface goes spongy with just the free carbon in the cast iron left on the surface. We lost a pair of small flywheels this way.

Sheet metal parts that are 'ovened' we usually get shot blasted then immediately Zinc sprayed, cast stuff depends on what we are doing with them, but anything cast will go rusty as you watch if it is shot blasted as there is water vapour in the shot blasting air and nothing to prevent immediate rust formation.

Zinc spraying is a gas flame process where Zinc wire is melted in a gas flame at high pressure and blown onto the heated and shotblasted surface, so no water vapour and a very good bond.

Pictures of some parts are on the trailer pages of our website:

http://www.oldengine.org/members/diesel/Trailer/trailer3.htm

Wet-stripped parts are washed off and dipped in an inhibitor which has to be removed before painting.

Of the two processes, the oven is probably better if you haven't got to worry about distortion of any parts, while the wet process is OK as long as you watch solution strengths. Electrolysis is another process which has applications here as well, but that is another subject entirely!

Peter

[biobill]

probably not the way you want to go, but i've got mine about half stripped simply by running home brew biodiesel in the stock tank, petcock and fuel line. had a nice "wrinkle" look for a while but now it's coming off in sheets.