limescale

share hints, tips and experiences
Post Reply
Obscured by clouds
Posts: 715
Joined: Mon Apr 06, 2009 3:23 pm
Location: north Wales

limescale

Post by Obscured by clouds »

several years worth of Lime rich water at farmworth resevoir has left Sibrwd [the N18] with a bad case of fur-ing. The hull around the waterline resembles the inside of a Kettle in a hard water area - which i now have to get off.

A not too gentle application of a surform made some impression as this 60 grade sandpaper, but there's a lot to do and it's not that good a removal.

So my question to the panel is - is there anything out there I can apply which will gently dissolve that crud [calcium carbonate aka flowstone] from the hull or will I have to endure clouds of quicklime as I scrape grind and shred the stuff off?
Tony



MR 2404 Julia Dream
N18 276 Sibrwd [ongoing project]
Hirondelle catamaran Kalipse
[down to 3!]
Rupert
Posts: 6255
Joined: Thu Sep 16, 2004 8:40 pm
Location: Cotswold Water Park

Re: limescale

Post by Rupert »

Calgon?
Rupert
Michael Brigg
Posts: 1663
Joined: Fri Jul 06, 2007 7:11 pm
Location: Gosport, UK

Re: limescale

Post by Michael Brigg »

Since the scale was put there by rainwater, (ie a very weak solution of a weak acid; (Carbonic acid) you can safely asume that any mild or weak acid will take it off.

Vinegar is unlikely to hurt. If it's wood, then perhaps oxalic acid, but be aware it will possibly bleach the exposed wood. Citric acid (Lemon juice) might work as well but the weaker organic acids will be much slower and may form equally insoluoble complexes from the derived calcium salt. Your scale may also contain other metals such as Magnesium and Copper etc, which may cause discolouration.

To avoid that problem, if you are on varnish I would do a test area first and then go for a DILUTE mineral acid with a universally soluoble anion such as Chloride.(eg Battery acid). Alternatively you could make a dilute (say 1:1000) solution of sulphuric acid (aka "Flowers of sulphur" used for clearing drains and disposing of corpses.) It will do the trick quicker but be ready with plenty of water to rinse it away once the job is done.

The most important secret is titration. Use just enough acid to do the job, as the scale will neutralise the acid and prvent any harm to surrounding structure. If the surface bubbles steadily your about right. If it foams and fizzes throw a bucket of water on it and rinse well, dry off and try adain at lower dilution.

Calgon is good for kettles and washing machines but is basically a Sodium Bicarbonate, and is only activated to acid by boiling, so it won't work in this situation.


To avoid damage to the hull it's just a simple matter of titration.
Michael Brigg
Graham T
Posts: 159
Joined: Fri Jan 23, 2009 1:45 pm
Location: Newcastle upon Tyne
Contact:

Re: limescale

Post by Graham T »

When I ran a boatyard on the Avon we used to clean limescale from the waterline with a toilet cleaning liquid but I cannot remember which one it was...
Graham T
Osprey 1340, Osprey 1245, Osprey 55, Miracle 1358, Laser heap, ancient Mirror kit half assembled, Project Miracle in need of decks........
Kielder Water Sailing Club
Obscured by clouds
Posts: 715
Joined: Mon Apr 06, 2009 3:23 pm
Location: north Wales

Re: limescale

Post by Obscured by clouds »

Luckily there's no varnish or wood - It's on GRP
Tony



MR 2404 Julia Dream
N18 276 Sibrwd [ongoing project]
Hirondelle catamaran Kalipse
[down to 3!]
Rupert
Posts: 6255
Joined: Thu Sep 16, 2004 8:40 pm
Location: Cotswold Water Park

Re: limescale

Post by Rupert »

Harpic with limescale remover does wonders on our loos, and we live in a very high limescale area.
Rupert
Bill-Conner
Posts: 126
Joined: Thu Sep 02, 2010 3:08 pm

Re: limescale

Post by Bill-Conner »

Wouldn't a jet wash do it? Seems to shift most things.
Pat
Posts: 2555
Joined: Mon Sep 27, 2004 1:42 pm
Location: West Wiltshire (Wessex)

Re: limescale

Post by Pat »

I don't recommend the jet wash on a painted boat - removes paint very well!
Bill-Conner
Posts: 126
Joined: Thu Sep 02, 2010 3:08 pm

Re: limescale

Post by Bill-Conner »

Possibly but her specifically says it is on a GRP boat!
Mungo
Posts: 133
Joined: Thu Oct 22, 2009 2:45 am
Location: Canada

Re: limescale

Post by Mungo »

I live in an area with very hard water and calcium scale is a problem with sinks, showers, toilets, kettles etc. We use a product CLR (http://www.jelmar.com/CLRbasic.htm) that is very effective. The MSDS link on that page tells you whats in it. I use it regularly in an aquatic facility to clean scale off tanks and pump impellers etc. It does require some soaking but I just saturate a rag with a 30% solution and lay it over the area for 15 minutes and the scale comes off quite nicely with a plastic scrub pad. Not sure availability outside NA. Says it's ok for fibreglass boats but best to read what it is not compatible with (glass, aluminium), don't mix with bleach or fire...

We clean coffee makers kettles etc with a 30% solution of white vinegar, but heat is involved. 30% works much better than a 50% solution, some chemistry thing likely involved...
JimC
Posts: 1721
Joined: Sun Oct 03, 2004 10:24 pm
Location: Surrey
Contact:

Re: limescale

Post by JimC »

Mungo wrote: The MSDS link on that page tells you whats in it.
Well, to approximate Mungo's recipe buy a bottle of lactic acid from a homebrew supplier, add about one part lactic acid solution to 10 parts of water and add a squeeze of washing up liquid to mimic the surfactants...
Obscured by clouds
Posts: 715
Joined: Mon Apr 06, 2009 3:23 pm
Location: north Wales

Re: limescale

Post by Obscured by clouds »

thanks guys.

think a spot of harpic will be the first course of action
Tony



MR 2404 Julia Dream
N18 276 Sibrwd [ongoing project]
Hirondelle catamaran Kalipse
[down to 3!]
Post Reply