Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 15-12-2017, 22:06   #1
Cruiser

Cruisers Forum Supporter

Join Date: Feb 2014
Location: Mcleans Ridges NSW Australia
Posts: 25
Acid washing topsides of GRP boat

A broker told me of a boat that's been refitted to look like new. He went on to say that the topsides were acid washed then polished and they are "gleaming".
I was of the opinion that acid washing fibreglass boats damages the gelcoat.

Any comments would be appreciated.
__________________

__________________
frankie46 is offline   Reply With Quote
Old 15-12-2017, 23:46   #2
Marine service provider
 
newhaul's Avatar

Cruisers Forum Supporter

Join Date: Sep 2014
Location: puget sound washington
Boat: 1968 Islander bahama 24 hull 182, 1963 columbia 29 defender. hull # 60
Posts: 4,692
Re: Acid washing topsides of GRP boat

Muratic acid
It cleans off all of the oxidation. Then you just rewax it
__________________

__________________
Non illigitamus carborundum
newhaul is offline   Reply With Quote
Old 15-12-2017, 23:55   #3
registered user
 
HankOnthewater's Avatar

Cruisers Forum Supporter

Join Date: Dec 2012
Location: West Australia
Boat: plastic production yacht, suitable for deep blue water ;)
Posts: 368
Re: Acid washing topsides of GRP boat

When I was working with fibreglass we made tanks to hold very strong acids. But as you may know there are many different kind of resins around. Some better than others.
here is a link at random: Storing Sulfuric Acid Using Fiberglass as a Material of Construction - Beetle Plastics

Damaging gelcoat? Doubt it, but firstly of course depends what acid is used. I think the common ones for cleaning are Oxalic acid, Phosphoric acid and Citric acid. For cleaning purposes on boats, I have only used the former one.

In my view, they do not affect the gelcoat at all. Yes these acids will remove any wax that is on the hull. The acid may leave some white residue, if the cleaned parts are not properly rinsed. These acids remove rust stains and the brown 'haze' close to the waterline.

As the diluted acid drips down the hull (ie from the deck, rigging, or railing) they drip then onto and along the antifoul. The antifoul can then show whitish streaks. In theory it may reduce the effects of the antifoul, but in practice, I have never noticed diminished efficiency of the antifoul.
__________________
Wishing you all sunny skies above, clear water below, gentle winds behind and a safe port ahead,
and when coming this way check http://www.cruiserswiki.org/wiki/Albany,_Australia
HankOnthewater is offline   Reply With Quote
Old 16-12-2017, 05:32   #4
Registered User
 
Fiveslide's Avatar

Join Date: Dec 2009
Boat: JBW club 420, MFG Bandit, Snark
Posts: 664
Re: Acid washing topsides of GRP boat

Quote:
Originally Posted by HankOnthewater View Post



As the diluted acid drips down the hull (ie from the deck, rigging, or railing) they drip then onto and along the antifoul. The antifoul can then show whitish streaks. In theory it may reduce the effects of the antifoul, but in practice, I have never noticed diminished efficiency of the antifoul.
Diluted is the key word here. I wouldn't go at a boat with full strength acid. I do smaller sections at a time so the acid isn't on their too long.

I've acid washed my bandit and 420 several times. Makes them look great every year, like I keep them under a shelter and take care of them. They actually look like they don't spend summers on the shore behind the house and winter's under some pine trees, uncovered at all times.
__________________
Fiveslide is offline   Reply With Quote
Old 16-12-2017, 05:43   #5
Registered User

Join Date: Oct 2015
Posts: 563
Re: Acid washing topsides of GRP boat

Quote:
Originally Posted by newhaul View Post
Muratic acid
It cleans off all of the oxidation. Then you just rewax it
YEP those toilet bowl cleaners
__________________
geoleo is offline   Reply With Quote
Old 16-12-2017, 07:17   #6
Registered User
 
Suijin's Avatar

Join Date: Feb 2013
Location: Annapolis MD; currently in Oriental NC
Boat: Valiant 40
Posts: 3,195
Re: Acid washing topsides of GRP boat

Mary Kate ON/OFF is nothing but acid. Super at cleaning gelcoat, including getting rust stains out. You dilute it pretty aggressively. Pretty much every yard I've been to uses it or it's equivalent to clean decks.
__________________
Suijin is offline   Reply With Quote
Old 16-12-2017, 07:49   #7
Senior Cruiser

Cruisers Forum Supporter

Join Date: Mar 2007
Location: Santa Cruz
Boat: Boatless Again
Posts: 4,483
Re: Acid washing topsides of GRP boat

Older gelcoat gets porous, and picks up a brown mustache from things like tanin in the ICW. The fix is to acid wash with oxalic and then fill the pores with wax. Repeat as often as needed.
__________________
donradcliffe is offline   Reply With Quote
Old 16-12-2017, 08:21   #8
Marine service provider
 
newhaul's Avatar

Cruisers Forum Supporter

Join Date: Sep 2014
Location: puget sound washington
Boat: 1968 Islander bahama 24 hull 182, 1963 columbia 29 defender. hull # 60
Posts: 4,692
Re: Acid washing topsides of GRP boat

Quote:
Originally Posted by geoleo View Post
YEP those toilet bowl cleaners
muratic is an ingredient in many crapper cleaners. I purchase mine full strength by the gallon.( cleans the dink of barnacles really good to.)
__________________
Non illigitamus carborundum
newhaul is offline   Reply With Quote
Old 16-12-2017, 08:38   #9
Registered User
 
CarinaPDX's Avatar

Join Date: Jan 2010
Location: Portland, Oregon, USA
Boat: 31' Cape George Cutter
Posts: 1,744
Re: Acid washing topsides of GRP boat

It should be clear from this that while the acid doesn't remove good gelcoat, it does remove the oxidized gelcoat. This in turn sets it up for further oxidation, so over time gelcoat is lost. Acid cleaning without sealing with wax or resin will probably accelerate gelcoat loss, so definitely keep up the seal as much as possible.

Greg
__________________
CarinaPDX is offline   Reply With Quote
Old 16-12-2017, 09:33   #10
Registered User
 
Sonosailor's Avatar

Join Date: Mar 2003
Location: Fredericton, NB, Canada in the summer and fall; Caribbean in winter and spring aboard Cat Tales.
Boat: FP Tobago 35 (and a H-21 SE)
Posts: 553
Images: 8
Re: Acid washing topsides of GRP boat

On/Off is just acid, diluted muriatic, I think. It is almost necessary for getting waterline tannin off white hulls before waxing. I do have something to add, however. In the islands, when you hire a local to wash and wax or just to wash, in some of the boatyards, what they do is splash muriatic or Ospho, then wax. No elbow grease for them. However, they pit your rubrails, your toerails, your through-hull fittings. We need to specify what can be used, or completely supervise these people.
__________________
Sonosailor is offline   Reply With Quote
Old 16-12-2017, 09:36   #11
Registered User

Join Date: Feb 2011
Location: France, britanny
Boat: Gibsea 302, 9m
Posts: 83
Re: Acid washing topsides of GRP boat

oxalic acid is not very dangerous, I use it for years
let it bleach the hull few minutes, then rinse thoroughly, polish lightly, and apply a wax.
__________________
bil56 is offline   Reply With Quote
Old 16-12-2017, 13:13   #12
Moderator
 
Paul Elliott's Avatar

Cruisers Forum Supporter

Join Date: Sep 2006
Posts: 4,165
Images: 4
Re: Acid washing topsides of GRP boat

Muriatic acid can be purchased cheaply where swimming pool chemicals are sold. It's really just another name for hydrochloric acid, but when sold as muriatic acid it's usually more dilute.

Oxalic acid can be found as "Wood Bleach" at the hardware store. It's a box of white crystal powder that you mix with water. "Barkeeper's Friend" contains oxalic acid.
__________________
Paul Elliott, S/V VALIS - Pacific Seacraft 44 #16 - Friday Harbor, WA
www.sailvalis.com
Paul Elliott is offline   Reply With Quote
Old 16-12-2017, 15:08   #13
Certifiable Refitter/Senior Wannbe
 
Wotname's Avatar

Cruisers Forum Supporter

Join Date: Jan 2008
Location: South of 43 S, Australia
Boat: Van DeStat Super Dogger 31'
Posts: 7,660
Re: Acid washing topsides of GRP boat

Quote:
Originally Posted by newhaul View Post
muratic is an ingredient in many crapper cleaners. I purchase mine full strength by the gallon.( cleans the dink of barnacles really good to.)
What final percentage solution do you use for cleaning gelcoat?

Around here bulk muratic is sold at 33%.
__________________
All men dream: but not equally. Those who dream by night in the dusty recesses of their minds wake in the day to find it was vanity: but the dreamers of the day are dangereous men, for they may act their dreams with open eyes, to make it possible. T.E. Lawrence
Wotname is offline   Reply With Quote
Old 16-12-2017, 15:25   #14
Marine service provider
 
newhaul's Avatar

Cruisers Forum Supporter

Join Date: Sep 2014
Location: puget sound washington
Boat: 1968 Islander bahama 24 hull 182, 1963 columbia 29 defender. hull # 60
Posts: 4,692
Re: Acid washing topsides of GRP boat

Quote:
Originally Posted by Wotname View Post
What final percentage solution do you use for cleaning gelcoat?

Around here bulk muratic is sold at 33%.
I use it full strength just don't let it get on painted surfaces you don't want stripped clean off.
__________________
Non illigitamus carborundum
newhaul is offline   Reply With Quote
Old 16-12-2017, 15:39   #15
Cruiser

Cruisers Forum Supporter

Join Date: Feb 2014
Location: Mcleans Ridges NSW Australia
Posts: 25
Re: Acid washing topsides of GRP boat

Hi There

The fibreglass tanks you used to store acids were they made using epoxy resin?

Happy days Sailing
Frank
__________________

__________________
frankie46 is offline   Reply With Quote
Reply

Tags
boat, washing

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
If I paint the boat, will I stop getting streaks down the topsides? yachtshah Construction, Maintenance & Refit 8 19-05-2017 23:06
Painting Wooden Boat topsides sole2248 Our Community 4 23-05-2013 20:56
Cleaning / Washing Sails - Washing Machine ? Bleach ? dennisail Deck hardware: Rigging, Sails & Hoisting 19 24-05-2010 22:16
Washing Clothes and Washing Machines Talbot Liveaboard's Forum 19 30-09-2009 08:38
Buffing/Waxing Topsides without hauling? ssullivan General Sailing Forum 26 26-04-2006 11:12



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 14:20.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2018, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2018, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.