prop-defender

[Andrew M]

Yep, agree with all above, I think the universally available UK brick cleaners are around the 6% - 12% area, I certainly haven't seen anything on general sale at 20% like the Agua Fuerte. that "hydrochloric 36" is a 36% mix but I had to register a trade account to get it so maybe that grade isn't for public.

 

[Richard.C]

Hi Richard,

I use acid to clean up Hollywood's stern gear, as mentioned above it is so easy. I've tried the Brick /mortar cleaners and they do work well enough but then bought some "Hydrochloric 36" from a specialist chemical company and that is super quick at removing the deposits left after the lift jetwash (I only use on the stern gear and platform mechanism). I think the effectiveness is all down to the acid %age. With the brick cleaners the 1st one I used was Everbuild , I think from Wickes, but then I found a higher %age one from Jewsons, Their own make , and that worked better. But then I got this "36" and that is just great, but be careful it is also really really wicked stuff, it almost snarls at you when you pour it into a jug. I also just paint brush it on and keep it moving and fizzing/foaming. Wash off with copious quantities of water. Also, all of them obvs demand full protective gear.
Here's a couple of pics showing the sterngear afterjetwash and then after acid clean and some polishing, you can see how the acid has cleaned away deposits and before polishing on some blades of the s/b prop (a couple have been polished in that pic) and P bracket.

Thanks Andy,

Looks like I need to go shopping for some Hydrochloric acid. My normal scrape and polish takes me 10-12 hours to get a finish I'm happy with.

Unfortunately as I needed to pay for a company to do all the bottom work during lock down I'm expecting they used power tools which have no doubt created some scratches and made it easier for critters to attach themselves.

 

[Richard.C]

Here is another pic of the bottle

View attachment 99833

As you can see , in Spanish, it is called acido clorhidrico which translates into hydrochloric acid in English.
And the concentration is 20%

I have heard of people using stronger concentrations and saying that they work even better.
Maybe the "Hydrochloric 36" mentioned above is 36% ?????

Safety
Yes, you do have to be very careful with the stuff.
Usually, I only wear shorts and Tee shirts but I also wear eye protection glasses and thick rubber gauntlet gloves.
I buy the gloves locally from our local fisherman's co-op - dirt cheap and really "up to the job"
You can tell that it is nasty stuff.
After an hour or so, the only parts left to do are the tops of the P Brackets (the P Bracket's flange that screws to the bottom of the boat).
To do these, you have to paint the Aguafuerte upside down.
This means that the acid runs down the brush and over the gloves.
We try to roll the gauntlet part of the glove to stop it running any further but I always get some on my skin.
And after a while, it itches.
I really wouldn't want to get it in my eyes.

EDIT
Oh yes - any that drops onto the concrete fizzes as it reacts with the cement.

And I thought the two part teak cleaner was nasty stuff!

 

[Hurricane]

And I thought the two part teak cleaner was nasty stuff!

Yep that can be uncomfortable as well if you clean the decks in bare feet with the two part cleaner.

 

[Hurricane]

Thanks Andy,

Looks like I need to go shopping for some Hydrochloric acid. My normal scrape and polish takes me 10-12 hours to get a finish I'm happy with.

Unfortunately as I needed to pay for a company to do all the bottom work during lock down I'm expecting they used power tools which have no doubt created some scratches and made it easier for critters to attach themselves.

Yep I had the same problem - fine scratches but over time, they can be polished out.
I use a 4" angle grinder with felt pads.
In fact, I use two angle grinders with felt pads - a "putter onner" and a "taker offer".
And a kit like this
POLISHING KIT 66 - FELT (ANGLE GRINDER KIT) FOR ALUMINIUM, ALLOYS, COPPER, BRASS | eBay
I tend to get through the polish so I buy more polish than discs
I've tried different colour polish - the brown seems to work well.
See here
Metal Polishing Buffing Compound Pro-Max Quality 100g - 750g Bars | eBay

When I do it, I run one angle grinder (the putter onner) and hold the polish block against the rotating disc.
Then apply the polish to the prop/metalwork.
Then finish off by buffing it with the other angle grinder's clean disc.
The initial polish took me a long time but now two or three hours after the boat is blocked off will achieve this:-