Which discs for Angle Grinder to clean prop

[jimi]

I’m reluctant to put hydrochloride acid near bronze as my elementary chemistry would suggest a corrosion risk. My experience of the cleaning pads on the angle grinder I was lent last year showed no damage or erosion to the prop so I’ll stick with that idea. Thanks all for the ideas , partic those who pointed me in the correct direction for the cleaning pads. Ps there is a place for hydrochloric acid on a boat.. down the toilet

 

[SDerbyshire]

Last auturm we used brick acid cleaner and it removed a lot of the ‘white worm’ deposits from Bonito’s prop

Last month i had a lift and scrub and used ‘scotchbrite’ style pads on my cordless makita, worked very well although could not reach the inner edges of the blades due to the size of the grinder.

 

[vyv_cox]

I’m reluctant to put hydrochloride acid near bronze as my elementary chemistry would suggest a corrosion risk. My experience of the cleaning pads on the angle grinder I was lent last year showed no damage or erosion to the prop so I’ll stick with that idea. Thanks all for the ideas , partic those who pointed me in the correct direction for the cleaning pads. Ps there is a place for hydrochloric acid on a boat.. down the toilet

Hydrochloric acid at the dilution you can buy in DIY outlets will not even stain brass or bronze. Stainless steel could be attacked by concentrated HCl after fairly long exposure but fouling is normally gone in 5 minutes anyway.

 

[vyv_cox]

These are some fittings I bought for an article in YM in 2011. They are 60/40 brass, DZR and bronze. Plasticine dams on each fitting contain 6% w/w hydrochloric acid.

I tested the fittings against a number of household chemicals, trying to find a method by which they could be differentiated easily. Unsuccessful unfortunately. This extract from the article.

Chemical resistance​

The chemicals available to the householder are weak substances and we didn’t hold out much hope for this one. Our fears were justified when nothing had any effect.
We tried:

Hydrochloric acid, killed spirits. Concentration < 10%
Ammonia solution. Concentration < 5%
NTA (nitrilotracetic acid) ceramic hob cleaner
Citric acid based hob cleaner
Glycolic acid based super powerful toilet cleaner.
Phosphoric acid based kettle de-scaler

We tested the fittings by forming a small dam with Plasticine on a suitable surface, then pouring in the chemical and leaving for 10 minutes. The hope was that the rectangular shape would be obvious when the dam was removed but in practice we failed to see any change. Later we dipped the fittings in the products for up to 30 minutes, with no more success.

 

[Daydream believer]

I’m reluctant to put hydrochloride acid near bronze as my elementary chemistry would suggest a corrosion risk. My experience of the cleaning pads on the angle grinder I was lent last year showed no damage or erosion to the prop so I’ll stick with that idea. Thanks all for the ideas , partic those who pointed me in the correct direction for the cleaning pads. Ps there is a place for hydrochloric acid on a boat.. down the toilet

I would be more worried about the microscopic scratches in the surface of the prop from the abrasive, than anything the brick cleaner does.

 

[AntarcticPilot]

View attachment 164346
These are some fittings I bought for an article in YM in 2011. They are 60/40 brass, DZR and bronze. Plasticine dams on each fitting contain 6% w/w hydrochloric acid.

I tested the fittings against a number of household chemicals, trying to find a method by which they could be differentiated easily. Unsuccessful unfortunately. This extract from the article.

Chemical resistance​

The chemicals available to the householder are weak substances and we didn’t hold out much hope for this one. Our fears were justified when nothing had any effect.
We tried:

Hydrochloric acid, killed spirits. Concentration < 10%
Ammonia solution. Concentration < 5%
NTA (nitrilotracetic acid) ceramic hob cleaner
Citric acid based hob cleaner
Glycolic acid based super powerful toilet cleaner.
Phosphoric acid based kettle de-scaler

We tested the fittings by forming a small dam with Plasticine on a suitable surface, then pouring in the chemical and leaving for 10 minutes. The hope was that the rectangular shape would be obvious when the dam was removed but in practice we failed to see any change. Later we dipped the fittings in the products for up to 30 minutes, with no more success.

I have cleaned a Gori folding propeller using laboratory HCL, diluted to around 10%. It worked fine, and even overnight soaking left no staining or corrosion.

@vyv_cox will correct me if I've got this wrong, but I think marine brasses are solid solutions, and so not liable to internal electrochemical effects between different elements in the metal (of course, they are affected by external electochemical effects), and are more resistant chemically than the component metals. I would not really consider the effect of HCl on brass to be worth even thinking about.

 

[rogerthebodger]

The Hydrochloric Acid I use is really for adjusting the PH level of swimming pools and is a much higher concentration that the brick cleaner you get in the UK.

I think its more like 30% concentration and I use it for derusting and fouling removal of prop and bow thruster prop

 

[vyv_cox]

The Hydrochloric Acid I use is really for adjusting the PH level of swimming pools and is a much higher concentration that the brick cleaner you get in the UK.

I think its more like 30% concentration and I use it for derusting and fouling removal of prop and bow thruster prop

Hydrochloric acid concentrations can often mislead (not that I am suggesting this applies to your post). Concentrated HCl is the maximum weight of gas that will dissolve in water, 39%. Some sellers dilute this by adding further water, for example 1 part acid to 4 parts water, and call it 20%. The actual concentration of HCl is about 6-7%. It can be difficult to know exactly what is being bought, but the red bottles sold all over Europe for domestic use are likely to be around this figure.

 

[rogerthebodger]

Hydrochloric acid concentrations can often mislead (not that I am suggesting this applies to your post). Concentrated HCl is the maximum weight of gas that will dissolve in water, 39%. Some sellers dilute this by adding further water, for example 1 part acid to 4 parts water, and call it 20%. The actual concentration of HCl is about 6-7%. It can be difficult to know exactly what is being bought, but the red bottles sold all over Europe for domestic use are likely to be around this figure.

Yes Vyv that is why I said "I think"

The acid I use is mainly for adjusting the PH of a swimming pool following the addition of Chlorine as a sanitizer.

Its available in every DIY /pool shop in South Africa so very easy and cheep to get

 

[Daydream believer]

I am lucky that I have circa 20 litres of brick cleaner from my building business, purchased about 45 years ago. It was available commercially then & is significantly stronger than any brick cleaner that I have been able to obtain from current builders merchants. I often use it when model making, for cleaning parts. A task for which it is emminently suitable. The fumes are a killer though & I have to be very careful.

 

[Habebty]

Have been using B&Q brick cleaner at the strength it comes out of the container for years on the prop and heat exchanger. I always rinse off after a few minutes then for the prop (2 blade folder) , use wet and dry to burnish. Quick and easy.

 

[vyv_cox]

Yes Vyv that is why I said "I think"

The acid I use is mainly for adjusting the PH of a swimming pool following the addition of Chlorine as a sanitizer.

Its available in every DIY /pool shop in South Africa so very easy and cheep to get

French swimming pool HCl seems to be either 23 or 30%, which as you say is probably the 'correct' description.

 

[RivalRedwing]

A light sand with a bit of wet and dry then a further coat of Velox, no need to sand right down or disturb the primer....

 

[jimi]

Quite happy for someone to demonstrate the efficacy of brick cleaner on my prop when it’s out the water in just over a week

 

[PaulRainbow]

Quite happy for someone to demonstrate the efficacy of brick cleaner on my prop when it’s out the water in just over a week

Take it off and bring it to Ipswich and i'll give you a demo

 

[jimi]

Take it off and bring it to Ipswich and i'll give you a demo

Might just do that I’m in Levington presume you are Yacht Haven?

 

[Rhylsailer99]

I wouldn't use grinding disks. A wire cup brush would be a better choice.

Try some brick acid first.

Brick acid very strong with wallpaper paste mixed in and paste it on the prop. Then you wont need to remove it.

 

[PaulRainbow]

Might just do that I’m in Levington presume you are Yacht Haven?

Yes, Ipswich Haven Marina.

 

[William_H]

Back to OP question re angle grinders. You hopefully will get a rubber backing pad so that a disc of abrasive paper can be attached. I find this far more useful than the usual cutting off disc. All sorts of abrasive levels are available. ol'will

 

[bignick]

I also use brick cleaner, purchased from Toolstation, following the advice on here.
This thread has got me wondering though, whether Coca Cola would be a viable alternative. Seems effective on brass and copper.