Conference unifix::sailing

	If the scale doesn't interfere with the normal travel of the piston,
	its probably safe to use brutal means (e.g. hammer and cold chisel) to
	remove the crud. You will damage the cylinder some, but (if you are
	careful) the damage will only be above the piston, where it won't
	affect operation. (If the cylinder is not metal, you may crack the
	whole cyclinder if you're not careful.)

	If you wan't to remove the crud by chemical means, you need to identify
	the materials involved and find something that will dissolve the crud,
	but not the cylinder. What's the cyclinder made of?

	--RS

re .0:

I'm not sure what causes this scale, but it does form in the pumps and 
outlet hoses, and, after a while (years), can completely block the
hoses. I've heard that the scale forms faster in warmer places (anywhere
south of New England). The scale that built up in my outlet hoses wasn't
very stout stuff mechanically. It could be broken fairly easily, so as
the previous reply suggests, brute force might work. If you don't
already have the replacement parts or if the parts aren't available
readily, you might consider installing an entire new head. (Our Raritan
PH has served well for 10 years.) We keep a rebuild kit on the boat just 
in case .....

    The scale found in the bottem of tea pots and steam irons is usually
    a carbonate of some sort. The usual method used to remove this stuff
    is soak it in a vinager (sp?) solution. There are also some 
    prepariations for removing the scale found in dishwashers on the 
    market. If all else fails a gentle application of Ajax might work.
    Good Luck, John W.

Thanks for the replies.  The cylinders are bronze.  My partner has been trying 
to use something to scrape the stuff out with but it is too hard to reach.  The 
blockage is nearer the bottom of the cylinder.  The piston stops at the scale 
and prevents the shaft and handle from moving up very far.  The top of the 
cylinder hits the handle and does not allow a very big opening to get a screw 
or other persuader down to the blockage.  It is essential we get the cylinders
apart so they can be tumbled and polished.  My partner has the facility to do 
at his work place.  Replacement is not an option at this point since he wants 
to keep the boat is as original condition.  The heads are vitreous china and in
generally good shape.  They have not been maintained very well, never in the 
past 5 years.  We will try the vinegar solution to see how that works.  I had 
not thought of checking the hoses as well.  I am sure they are somewhat less 
effective than when new.  Thanks all for the replies.  I will post the outcome
here.  Thanks Alan for modifying the keyword also.  Maintenance is a much better
spot than misc.  

Brian  

    I rebuilt both our heads last winter and was faced with the same
    residue.  I submerged both in trash cans filled with a strong vinegar
    and water solutions, then moved on to other projects for the better
    part of a month.  Returning to the task, I found the scale was easily
    removed with a stiff scrub brush and water.  I treated my 13 year old
    hoses to the same soaking, and found that after their bath and a good
    rap on the work bench, the scale came right out and renewed the
    flexibility to the old hoses.  It's a dirty job, but, somebody's......
    
    Bob

re .4 and .5:

Vinegar is weak acetic acid (if I remember correctly). I don't know if 
bronze would be damaged by prolonged immersion in vinegar, but it is 
possible as most metals are attacked by acids. 

    Re .4
    
    If your partner has tumbling/polishing facilities, might he also have
    ultrasonic cleaning/degunking ?  Ultrasound with commercial radiator
    flush solution might do the trick more quickly and safely (metalwise,
    .6).  Another option if you can remove or will be replacing rubbers,
    gaskets, etc. is to heat cylinders with a propane torch.  This will
    frequently crack deposits in cylinders (cleaned my baby blake that way)
    by crystalizing connective layer to a powder, breaking adhesion.
    
    Also, since your friend has tumbler, how about filling cylinders part
    way full of BB's and tumbling ?
    
    Good luck.
     

    
    Taking a trick from auto restoration you could probably try honing the
    cylinders. Depending on the diameter you could probably use a brake
    caliper hone (up to 2 1/2"). You can buy them at any auto repair shop 
    for around $30.00 or better still rent them from Taylor rental.  

    Well the task is complete.  We used a vinegar/water solution which
    seemed to work well enough.  After a few weeks of soaking, the gunk
    seemed to soften up enough to be easily forced out.  Now for the
    finishing.  Any recommendations on a good long lasting paint that can
    be used on bronze?  

    	I would use Rustolium without a primer. In fact, if you can remove
    anything that might melt from the unit, I would bake it after painting.
    This gives a much harder finish that is long lasting and beautiful.
    I used several coats of baked Rustolium white on my first childs hi-
    chair tray which lasted quite well. At least enough so that my very
    critical wife did not require its repainting when our third child came
    along. 
    	In any event, Rustolium comes in spray cans, is easy to find in
    most hardware stores, and is fairly inexpensive when you consider most
    things for marine use.
    	Hope this helps...John W.

    Bake at what temperature and for how long?  Thanks.
    

    	
    	Unfortunately, it was over fifteen years ago that I baked
    the high chair tray so my memory of what I did is sketchy. I
    think I would try 250 degrees F. for several hours.  This temp
    is hot enough to super dry the paint but not hot enough to scorch 
    it. Something else to consider is the density of the part to be
    baked.  A heavy item will need more time then a piece of sheet 
    metal.  I would experiment with items of like mass beforehand to
    get exactly the right combination.  Also, if you are using the 
    kitchen stove, remember to use the range hood as there are some
    fumes to contend with, not terribly nasty but there nontheless.
    If your stove is gas, be sure to dry the piece first or you might
    have a fire.  I used an electric stove but allowed the tray to 
    dry first anyway. And last, allow the piece to cool completely
    before handling as the paint will be imprintable when still hot
    
    
    Good luck, John W.
    

    A quick update here.  We have successfully disassembled the pump
    mechanisms and are in the process of cleaning, polishing, painting...
    The vinegar solution worked well enough to soften the scale in the
    cylinders allowing it to break up.  We received a recommendation to use
    Hydrochloric acid in mild solution to further dissolve the gunk and to
    help remove the paint.  The gunk is gone but the paint is still there. 
    My partner will be using a brake hone to finely polish the cylinder
    walls.  We will not be having the cylinders tumbled as previously
    stated.  Thanks for the replies!
    
    Brian