Phosphoric Acid, 3M 5200

[Funsail29]

I ran across a post in the wooden boat forum about flushing a heat exchanger with a solution of phosphoric acid and water at a mixture of 4 parts water to one part acid.
heat exchanger cleaning
Could a mixture of, say, 8 to 1 be used with a old tooth brush to scrub down things like the the stuffing box or through-hull valves? Then neutralized with a scrub of baking soda and water.
Would it be productive and practical?

Also, sometime ago there was a post by "Captforce", I believe, about making a paint-able mixture out of 3M 5200. Cant find it again.
What was it mixed with? acetone?

Thanks
Funsail29

[Hudson Force]

Yes, I did mention the thinning of 3M5200 for use as a paint. I've used 3M5200 thinned with acetone to paint the bildge and generator pallet in my engine room. I did this after seeing a marine knowledgable friend do the same. I've had it serve me well for ten years. Like any paint or coating, it will not adhere well if the surface is not prepped clean and dry. I am also careful to mix and apply the volatile materials in well vented space and without any risk of flame. As for the acid washes, I do some of this with the soultion as dilute as will function. Fiberglass hull stains, head parts, some with heat exchangers, but I'd rather use the soft nylon teather of a surfboard leash.

[Chief Engineer]

Wire brush stuffing boxes and thru hulls.

I have never heard of anyone acid washing their thruhulls....ever

[Pblais]

I have never heard of anyone acid washing their thruhulls....ever

Neither have I. Phosphoric acid is use to passivate stainless steel.

Cleaning them up should not require such extras. They may not hurt but a lot of things won't hurt yet yield no additional results.