Topic: frustrating phospate and oil bolt and hardware

[Bob Gaines]

About the flash rust problem, have you tried rinsing them in a soda ash ( baking soda ) to neutralize the acid, then dry?
When I strip parts in acid for plating or after a bath in Prep Etch ( makes really nice black bolts/screws ) I rinse in soda bath then rinse and dry. Stops my rust issues. Just rinsing in water doesn't get all the acid off. My experience the swimming pool biz helped me with this problem

What proportion would you suggest of water and baking soda for a 5 gallon bucket?

[1969 Cale II]

Tough question to answer. I do small batches of nuts/bolts. But, I would try 1 lb in 5 gallons of hot water. I like hot water because it evaporates faster. You really can't over use the soda amount, just rinse when done. Big parts need big volumes I understand that. My steps in prepping bolts is, soak in muratic acid long enough to remove all rust, rinse with water, then use a soda ash rinse, then rinse in hot water to help in drying and I don't have the flash rust problem. The neutralizing part happens real fast, 15 seconds to a minute is plenty. If I do small batch hardware, I just sprinkle powder right on the bolts and then a little water. Good rinse and things are done. I do use the air to blow off the rest of the water, I don't let water stay. You will find it is easy to do and maybe make things go better. I over do the soda part but it doesn't hurt anything.

[Bob Gaines]

Tough question to answer. I do small batches of nuts/bolts. But, I would try 1 lb in 5 gallons of hot water. I like hot water because it evaporates faster. You really can't over use the soda amount, just rinse when done. Big parts need big volumes I understand that. My steps in prepping bolts is, soak in muratic acid long enough to remove all rust, rinse with water, then use a soda ash rinse, then rinse in hot water to help in drying and I don't have the flash rust problem. The neutralizing part happens real fast, 15 seconds to a minute is plenty. If I do small batch hardware, I just sprinkle powder right on the bolts and then a little water. Good rinse and things are done. I do use the air to blow off the rest of the water, I don't let water stay. You will find it is easy to do and maybe make things go better. I over do the soda part but it doesn't hurt anything.

I will give it a try . I do know that flash rusting is not limited to items that have been taken out of the acid bath from personal experience. Bead blasted parts that I have rinsed prior to painting also would have a tendency to have a tinge of flash rust if I blew completely dry with compressed air rather then towel dry and finish with the compressed air.My concern is that once neutralized in the soda bath you have to rinse with regular water which puts you back to square one in regards to the flash rusting.

[jwc66k]

The "rinse" cycle is to stop the phosphating process, and to cool the parts for handling. I use a large wash tub with 8 to 10 gallons of water to lower contamination from the previously dipped parts. To dry them, replicate the warm, dry California sun. Try a heat lamp and a small fan on them, for 15 or 20 minutes to evaporate the remaining moisture, then oil. I sun dry on a towel. Compressed air has always left a rusty "flash" when I've tried it, and a warm oven is just as bad. Hot 20 or 30 weight stinks up anywhere it's used so I prefer WD-40. On moving parts like a hood hinge, I flush the joint with WD-40, catching it in a pan and back in a spray bottle for more flushing. Obviously when the joint runs clear, it's flushed.  I haven't experimented with baking soda to neutralize the acid from the bath.
Have you considered using shower rings on small parts with a hole? From bead blasting to spraying with oil they stayed "ringed". How about "plumbers tape", the multi-hole steel strip? This is for bead blasting only, I use a stainless multi-hole scoop for handling in the blackening dip, and a second scoop from the phosphating tank. A fish poaching pan works on long items like center links.
Jim 

[1969 Cale II]

When I use soda ash ( might be cheaper if you look for swimming pool chem sales places to look for ph up than buying baking soda at the store ) and rinse then dry I don't have rusting issues. I think the low ph level left on the part after rinsing and then hits the air is the culprit. Water is not enough to change the ph far enough. Using the swimming pool experience. ( what I do for a living ).
The worst thing I have done is use to much soda and not rinsed well enough and that freaked out thee plater, I justed rerinsed and problem solved. Left a white residue on parts.

[WT8095]

When I use soda ash ( might be cheaper if you look for swimming pool chem sales places to look for ph up than buying baking soda at the store ) and rinse then dry I don't have rusting issues. I think the low ph level left on the part after rinsing and then hits the air is the culprit. Water is not enough to change the ph far enough. Using the swimming pool experience. ( what I do for a living ).
The worst thing I have done is use to much soda and not rinsed well enough and that freaked out thee plater, I justed rerinsed and problem solved. Left a white residue on parts.

Minor clarification for those not familiar with these chemicals: soda ash is sodium carbonate, also known as washing soda. Baking soda is sodium bicarbonate. They can both be used to increase Ph (more alkaline). Sodium carbonate can get to a higher Ph, about 11 as opposed to 8-9 for sodium bicarbonate.