"Surface Conditioning" Metal

Here is the first group of small parts from the running gear that have been cleaned.

The process was:

• Wire wheel (bench grinder and angle grinder) all the paint and dirt away
• Electrolytic De-Rusting
• Two coats of SEM Rust Mort to kill the flash rust and protect the parts until they are ready for further treatment.

At this point, a restorer has to decide just how much an excellent paint job means to them.  These parts could be painted as is, or receive further treatment that will ensure the best paint job I can manage when the time comes.  All these parts are highly visible and may be considered ornamental as well as functional.  As a matter of fact, I intend to draw a certain amount of attention to them in the future paint scheme.  So it means a lot to me to have them ready to receive my best effort at painting.

Despite the fact that this carriage has actually been very little damaged by heavy rust, this macro shows that the surface of the metal is very rough.  I suspect it is a sand casting.

This roughness is not something that "paints out".  It will still be there after the last coat of paint is applied.

Unless I do something about it now.

3M makes a nifty product called "Scotch Brite Surface Conditioning Disc".

These discs "Velcro" onto a drill- or angle grinder-mounted pad, and they are used for smoothing surfaces.  Like sandpaper, they come in coarse, medium and fine.

Since I don't need aggressive scale removal or anything, I am just going to polish these surfaces up a bit with a fine disc.

The bottom part has been given a little polish-up.

These plates sit atop the springs and they're made to be pretty as well as functional.

Unlike automobiles, every bit of the running gear on a horse drawn vehicle is visible and forms a significant component of the visual pleasure of looking at the vehicle, if well treated.

No point putting these pretty things back on, painting, and then saying..."Well...THOSE are ugly!"

That's what poor surface preparation gets you.

There are no deep pits on the surface that would require a product like automotive body filler to fill.

Instead, I'm going to apply a very thin coat of automotive "spot putty", also called glazing compound.  This compound dries for sanding in about 15 minutes IF IT IS APPLIED VERY THIN.

Products seem to be changing all the time.  A spot putty that I used and really liked about four years ago is no longer being made.  This stuff seems to work pretty well.

Note that I have also treated the bolt head.  Anything that's visible (except maybe the nuts, which are in excellent condition) will be surfaced.

Once the spot putty is dry, I sanded the majority of it off with 220 grit dry, finishing up with 400 grit dry.

A wipe with degreaser and a tack rag, then a quick spray with Rustoleum rattle-can primer, and this part is ready to be carefully stored away in anticipation of re-assembly.

By the way, these two small marks, made with a Dremel tool and a burr, tell me that THIS part goes on the left spring, and THIS end of the part faces forward.

The right hand part has ONE mark on the forward-facing end of the part.

Also note the roughness of the un-conditioned underside of the part.

My next post should have the results of my visit with the blacksmith about those worn and broken bolts.  In the meantime, every visible surface of every piece of the running gear will receive the same surface conditioning treatment as this part has undergone.  That should keep me off the streets for awhile!