Restoring - General discussions that span across many different groups of years and models > Processes, Products & Techniques

Phosphating 101 -

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jwc66k:
I've been phosphating for over twenty years and this is what it entails. There's a lot of items involved in the phosphate and oil process. Remember, you are playing around with acid.
1. It only works on steel and iron parts so don't try it on aluminum, brass, copper or non-metallic items.
2. Items to be phosphated must be clean. More on that later.
3. Use only stainless steel tanks and tools. One exception is the rinse tank.
4. I preheat three gallons of water in my kitchen and pour what I need into the stainless tank heated by propane.
5. Store unused chemicals in HDPE containers.
6. I found that air drying works best, in temperatures above 72F, in the sun and with a bit of breeze prior to the oil step.
7. I don't recomend drying in an oven as it leads to rust forming. It may be a matter of timing, but air drying works.
Tools - (see pictures)
1. Stove. I like propane. Electric stoves don't seem to last, don't produce enough heat and are too small. You need at least 180F water to phosphate.
2. Tanks - All stainless steel. You can get them from restaurant supply stores, Wall-Mart types or e-bay. My rectanglular tank is big enough to do a hood hinge (12 3/4 X 11 5/8 X 3 7/8), but you have to "splash" the spring retaining arm. The fish poaching tank (19 1/2 X 6 3/4 X 4) works well on long items, center links, strut rods, etc, but you have to swap ends of the item after 45 seconds to a minute. The round pan is for metal blackening and the sauce pan (stainless) is for small batches, mostly nuts and bolts.
3. Tools - Goodwill. I got the long hook from a hardware store. It is stainless (all stainless is expensive). It was 36 inches lon and I cut it in half and promptly lost one piece. Bend as necessary.
4. Metal blackening - Eastwood. Just get the metal blackening solution as the rest of the stuff is a joke. Well, the HDPE container is nice to have.
5. Rinse - A number 3 wash tub works. I also use a plastic bucket for small batches.
Not shown:
- the phosphoric acid concentrate I use. More on that later.
- a 1 cup Pyrex measuring cup, to get the correct mixture from the phosphating concentrate. More on that later.
- a thermometer - a deep fat fryer type.
- stopwatch. It's important.
- a large 5 gallon plastic bucket (paint, dry wall, dish soap types) for used phosphate water. After the water cools and I don't have any small batches to do, I pour the water into a bucket with a couple of scoops of Borax to neutralize the acid.
- neoprene gloves.
- hooks made from coat hangers to air dry items.
- shop towels.
Jim

jwc66k:
Part two - Chemicals -

Metal blackening acid: Eastwood www.eastwood.com  Metal Black Concentrate replacement to get a dark looking part prior to phosphating. Mix 8oz concentrate and one quart water (Eastwood is very lax on their instructions) in a HDPE (High Density PolyEthylene, a number 2 in the recycle triangle) container with a HDPE lid, then pour what you need into a stainless steel mixing bowl. When you are done, you can pour the Eastwood black solution back in its container for reuse several times. Don't try any metal lids or aluminum foil in the lid, they corrode away. I used a glass container with a plastic lid for a while, don't bother. Rinse the mixing bowl in the rinse water when everything is done. The entire kit is a waste of time and money, it don't work and looks terrible.
(I left several bolts in this solution for an hour just to see what would happen. After phosphating I was surprised to find that after they were submerged in water for several days they looked great and did not rust. I intend on repeating the procedure.)

Phosphoric acid: E-Phos 630 for the phosphoric finish, available from: EPI www.epi.com There are other sources. I got mine thru the plating shop that does my clear and gold zinc plating. I don't know if EPI sells to the general public but they sell in bulk as in a case with 12 bottles. I don't remember the cost but my plater sold me two quarts and kept the rest as he was thinking of doing some phosphating for a customer. As it is a concentrate, I use 1 to 3 oz per gallon of water depending on what final results I desire. The mixture must be heated to over 180F to "cook" items properly.
I used another product called "Rust-Mort 69504" (the 4 equals a quart) from SEM Products  http://semproducts.com/ It's available from Amazon and many auto body shop supply stores. I "adapted" its use because the main ingredient is phosphoric acid. Again, I use 1 to 3 oz per gallon of water depending on what final results I desire. The only drawback is a fine lite layer of crystals that sometimes appears from the "cooking" process. 

Rinse water: right from the tap.

Oil: New motor oil, used motor oil, transmission fluid, WD-40. This is the tricky part.
- I tried heating new motor oil to 400-450F and succeeded in stinking up the neighborhood. Air temp clean oil seems to work sometimes if left parts are left for a day, but a hood hinge requires about three gallons of oil.
- Used motor oil has acid in it so you are defeating your goal. I've read that others use different "shades" of used to get the desired dark finish.
- Transmission fluid was suggested but I haven't tried it.
- WD-40. It works.

Arm and Hammer Borax laundry soap: used to neutralize the leftover phosphoric acid solution after it cools. A cup per gallon of water solution should do the trick. Let the water evaporate and then throw what remains in a garbage bag and then into the garbage. 
Jim

cobrajetchris:
Sounds complicated, dangerous, messy and expensive, I think I will just send my parts out for phosphating to someone like you that has experience. Do you offer this service or just do your own parts?

CharlesTurner:

--- Quote from: cobrajetchris on April 24, 2012, 11:52:02 AM ---Sounds complicated, dangerous, messy and expensive, I think I will just send my parts out for phosphating to someone like you that has experience. Do you offer this service or just do your own parts?

--- End quote ---

Phosphating is about one of the simplest coatings to work with.  I wouldn't consider it dangerous at all.

CharlesTurner:
Good write-up.  The only thing I would add is to make sure the parts are dry before coating in oil or whatever.  I usually blow-dry with compressed air before putting in an oil bucket.  I just use a straight 30W motor oil, new, nothing fancy and soak the parts for 24 hrs.  What's nice about soaking in oil is that it penetrates the phosphate surface.  Once I've gotten all the oil off with paper towels, I let them sit out for a while.  Can wash them with dish-washing detergent, which removes oil from the surface so it doesn't attract dust.

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