Today's discovery: GRP cleaner

[Hydrozoan]

... My assumption was that almost all colour comes from metal salts of some sort, and that this is a phenomenon of local penetration of the GRP, as you see with rust stains on deck.

I am inclined to doubt that metal ‘salts’ (trace metal solids would likely be oxides, hydroxides or hydroxycarbonates or hydroxycarbonates) are a dominant component of the brown waterline material in typical circumstances.

I suspect that the dominant component will be organic substances which concentrate in the sea surface microlayer, such as humic acids, hydrocarbons and phytoplankton exudates. Some of those may have an ability to complex trace metals, but I doubt that would be a cause of the brown colouration.

PS I think there is a tendency to extrapolate cleaning agent use on rather flimsy associations (such as colour, or apparent stain origin) when more thought about the possible nature of the offending material might help. I have previously given the example of an engine and machinery cleaner (detergent-based, non-abrasive) which I found far superior to conventional hull cleaners for removing grey streaks. I had been told that the streaks were probably aluminium from the toe rail, but read on a caravan forum a post by an observant chap who had noticed no grey streaking below his aluminium gutters, but lots across the back of the caravan - where there was no gutter. Surmising it was hydrocarbon material from traffic in rain in the suburban area in which he lived , he tried the engine and machinery cleaner with great success. (Proprietary road film cleaners would presumably do well, too.)

 

[JumbleDuck]

I am inclined to doubt that metal ‘salts’ (trace metal solids would likely be oxides, hydroxides or hydroxycarbonates or hydroxycarbonates) are a dominant component of the brown waterline material in typical circumstances.

I suspect that the dominant component will be organic substances which concentrate in the sea surface microlayer, such as humic acids, hydrocarbons and phytoplankton exudates. Some of those may have an ability to complex trace metals, but I doubt that would be a cause of the brown colouration.

Thanks. I have probably drawn unreasonable conclusions from the similarity of appearance and effects between rust and waterline stains.

 

[Marine Reflections]

I am inclined to doubt that metal ‘salts’ (trace metal solids would likely be oxides, hydroxides or hydroxycarbonates or hydroxycarbonates) are a dominant component of the brown waterline material in typical circumstances.

I suspect that the dominant component will be organic substances which concentrate in the sea surface microlayer, such as humic acids, hydrocarbons and phytoplankton exudates. Some of those may have an ability to complex trace metals, but I doubt that would be a cause of the brown colouration.

PS I think there is a tendency to extrapolate cleaning agent use on rather flimsy associations (such as colour, or apparent stain origin) when more thought about the possible nature of the offending material might help. I have previously given the example of an engine and machinery cleaner (detergent-based, non-abrasive) which I found far superior to conventional hull cleaners for removing grey streaks. I had been told that the streaks were probably aluminium from the toe rail, but read on a caravan forum a post by an observant chap who had noticed no grey streaking below his aluminium gutters, but lots across the back of the caravan - where there was no gutter. Surmising it was hydrocarbon material from traffic in rain in the suburban area in which he lived , he tried the engine and machinery cleaner with great success. (Proprietary road film cleaners would presumably do well, too.)

Indeed.

So just today, I was cleaning of the scale/tannin / TDS / build up/ whatever you want to call it from a dirty waterline on a Phantom 38 that has been on the Thames.

Whatever it was from the above, the de-scaling process prevailed.

I used a diluted solution of Spirit of Salts that got to the heart of the matter with multiple passes.

The boat was out of the water.

I used a paintbrush and a melamine sponge.

The most effective system seems to be Starbright's boat and barnacle remover.....Thus far on my travels.

Toilet cleaner is... as was posted very early on by LadyInBed a very effective solution also, and cheap to boot.

Folk will realise that surfaces either attract or they reject.

The waterline is the hardest test for testing of a rejecting surface, if one inclines to try creating one.

But imagine if you will cutting out the centre of a very good nonstick frying pan and glueing it to the waterline to see how it compares with what you currently have.

Times have moved on, and now superhydrophobic surfaces are everywhere...

Almost all of the above conditions require some de-scaling to get the surfaces back to raw condition.

Even a sheet of glass (which is very smooth and conditioned well) will pick up water drops from the shower and will eventually go chalky and difficult to clean.

When I speak of highs and lows.. we are speaking of at the microscopic level... those stains have to park somewhere.. even if we are talking of the slightest whiff of porosity, that is where they will fill.

What it takes to remove them is about the same effort as it takes to prevent them.

Wax will not work for long we have seen that, what stands the test of time (as prooved) is condition..

 

[Hydrozoan]

... So just today, I was cleaning of the scale/tannin / TDS / build up/ whatever you want to call it from a dirty waterline on a Phantom 38 that has been on the Thames.

Whatever it was from the above, the de-scaling process prevailed.

I used a diluted solution of Spirit of Salts that got to the heart of the matter with multiple passes. ...

Well if it was dominantly calcium carbonate scale (even if it was coloured brown by organic materials) it is hardly surprising that ‘spirits of salts’ or Harpic (which was LadyinBed’s precise suggestion) will do the job – the former is just an old name for hydrochloric acid, and Wiki says Harpic is 10% HCl. I haven’t checked the Starbrite product you mention, but hydrochloric acid will shift the calcium carbonate of barnacle plates, too. But of course any acid will dissolve calcium carbonate – including oxalic acid for that matter.

 

[Allan]

Like a number of people on this thread, I've got a lot of time for Mr Reflection, his work and input here is always useful.
When I had my boat I used oxalic acid. I never found it needed wallpaper paste, just a little washing up liquid. I stopped using it when I started worrying about two things:-
1. Many products or chemicals make plastic brittle. What is happening to the surface at a micro level?
2. The stain must have some substance. Watching it "disappear" it a few minutes doesn't mean it's gone, just that you can no longer see it.
Both of the above could have the effect of keying the surface for next year's stain.
My boat was in Cardiff bay and suffered from what is known locally as the "Cardiff stripe". To reduce this I prepared the hull as Mr Reflection suggests then went around the waterline many times with a good quality wax. It would not stop the stripe but would mean I could remove it easily with a soft brush.
Allan

 

[Marine Reflections]

Like a number of people on this thread, I've got a lot of time for Mr Reflection, his work and input here is always useful.
When I had my boat I used oxalic acid. I never found it needed wallpaper paste, just a little washing up liquid. I stopped using it when I started worrying about two things:-
1. Many products or chemicals make plastic brittle. What is happening to the surface at a micro level?
2. The stain must have some substance. Watching it "disappear" it a few minutes doesn't mean it's gone, just that you can no longer see it.
Both of the above could have the effect of keying the surface for next year's stain.
My boat was in Cardiff bay and suffered from what is known locally as the "Cardiff stripe". To reduce this I prepared the hull as Mr Reflection suggests then went around the waterline many times with a good quality wax. It would not stop the stripe but would mean I could remove it easily with a soft brush.
Allan

That's really good to hear, thanks! :encouragement:

 

[Marine Reflections]

Well if it was dominantly calcium carbonate scale (even if it was coloured brown by organic materials) it is hardly surprising that ‘spirits of salts’ or Harpic (which was LadyinBed’s precise suggestion) will do the job – the former is just an old name for hydrochloric acid, and Wiki says Harpic is 10% HCl. I haven’t checked the Starbrite product you mention, but hydrochloric acid will shift the calcium carbonate of barnacle plates, too. But of course any acid will dissolve calcium carbonate – including oxalic acid for that matter.

Yes. It seems despite what particles / chemicals / organics or metallics causing the staining at a waterline, the chosen/ effective method for removal is that of a de-scaling nature.
This is VicS's dept and I wish I paid attention more in chemistry.

 

[Allan]

Yes. It seems despite what particles / chemicals / organics or metallics causing the staining at a waterline, the chosen/ effective method for removal is that of a de-scaling nature.
This is VicS's dept and I wish I paid attention more in chemistry.

One of my points above disagrees with this. The last time I used Oxalic acid on my waterline I watched a small area very closely. The stain just disappeared, no fizzing, no running off, nothing. My conclusion was that I had just bleached the stain and whatever it had been was still there, just a different colour, maybe transparent? It was then I started the plan to polish and wax to produce a surface the stain would not stick to.
Allan
PS. Related to this thread, is there a list somewhere that relates the coarseness. or otherwise, of compounds like G3, G6 etc. to grit numbers? (1000, 1500, 2000etc)

 

[Marine Reflections]

Yes, it's quite possible to have it seem that way. A bleaching effect would be part of the action.

Depending on the depth of the offending accumulation, be it above the surface or within a surface, it may seemingly vanish as there is only the chemical conversion/bleaching action going on before a rinse may have dealt with it.
If however, the depth of the offending had built up some structure via scale, then again yes a bleaching action can take place, but un-dissolved structures can remain.
Oxalic is more for when the offending hasn't built up a structure as such, and stain removal/conversion is the goal. It can't replace a fizz that will break down structures.

Oxalic will eventually break these down, however, and so the bleaching effect would occur along the way.
As such, most structures seem to be able to be demolished via de-scaling products specifically as opposed to that of raw oxalic, IMO.

Viakal will slowly break down most scale structures and remove any from within the surface also. Harpic, as suggested by LIB, will have a similar grunt level.

Moving up the chemical grunt level of that family will activate more fizz, (sorry, that's the best chemical analogy I could think of, let's hope that's the actual term) but at a greater strength it carries a greater concern when handling, applying, rinsing, splashing on other surfaces or surroundings, air quality of immediate passers-by and you.

It does, however, fizz the scale at a rapid rate and would be the right choice if the environment and precautions correctly set up.

Hydrozoan
"Well if it was dominantly calcium carbonate scale (even if it was coloured brown by organic materials) it is hardly surprising that ‘spirits of salts’ or Harpic (which was LadyinBed’s precise suggestion) will do the job – the former is just an old name for hydrochloric acid, and Wiki says Harpic is 10% HCl. I haven’t checked the Starbrite product you mention, but hydrochloric acid will shift the calcium carbonate of barnacle plates, too. But of course any acid will dissolve calcium carbonate – including oxalic acid for that matter."

+1 What he said.

To highlight though, there is a huge difference in the level of hydrochloric acid found within Harpic, jumping to brick cleaner, again jumping to spirit of salts of which is the highest content.

As the opportunity has presented itself...
My concern is that all of the above deals with reversal, but at a cost. We will never be in a situation where we don't need products with grunt, but with pooled knowledge on what causes what, we can target that reversal more effectively and also understand how better to prepare/condition a surface from not needing too much grunt.

The waterline is only really a few inches wide around the whole boat; no area demands more attention/reversal than an accepting waterline. IMO it is the least conditioned and protected.

 

[Marine Reflections]

Related to this thread, is there a list somewhere that relates the coarseness. or otherwise, of compounds like G3, G6 etc. to grit numbers? (1000, 1500, 2000etc)[/QUOTE]

It kind of won't really help unless the material being worked on was standardised. What effect 1200 has on something would be different on another. Working on marble or cheese.

Working on gel coat the variables like the pad, action of the polisher, toughness/resistance of gel coat to one side, you really have three main types of grade, Coarse, Medium and Fine. For Farecla this would read G6 - G3 - G10

But I could work each with a soft pad or an aggressive firm pad on each and the results would be different.

If there were a standard, say with only one pad rotating at a certain speed/action, your coarse - med - fine would have a recordable difference, but this cant really be transferred over to a particle measuring principle due to some being diminishing particles or some simply being made from different materials.

Too many variables I'm afraid.

 

[Cactus Sailing]

oxalic acid in powder form on eBay, mix with wallpaper paste, does the job. Or if you grow rhubarb boil the green tops and when cool that works as well.

i have an excessive amount of rubarb, what do i do with it? boil it then turn it into a paste?

 

[BelleSerene]

i have an excessive amount of rubarb, what do i do with it? boil it then turn it into a paste?

I asked a doctor. Because it’s Friday and because one was available.

You want to break the cell wall down as the oxalic acid is very likely intracellular, so boiling would be a very good starting point. We know it’s resistant to boiling since it remains in cooked rhubarb crumble for example. It’s what creates that tooth-coating chalkiness.

Then if possible liquidise it to extract the maximum amount.

_{Because rhubarb is 95% water, its active ingredient for hull cleaning is relatively concentrated.}

Formula C₂H₂O_4.

​

Thanks doc.

Remember, it’s the leaves you want. The stuff is toxic, so do ventilate the place while boiling, and do wear gloves when handling it - certainly once it no longer looks like a rhubarb leaf.