Granville Rust Cure Heavy Duty 250ml

Granville Rust Cure Heavy Duty

Cost: 250ml – £10 (reviewed here),

1 litre – £20,

5 litres – £80.


There are many many rust treatments out there, most of them are chemical reactions to the rust particles and it somehow converts it. It’s clever, I’m not a chemist so I don’t know exactly how it works. Some are better than others, I Use POR15 for areas that need paint like under the fenders etc where something will get punishment. I have been advised POR that its is not designed or recommended to treat the whole car, like the painted surfaces. As a result I am looking for something that will do the job on the painted side. After speaking to Frost they advised me of this stuff called Granville Rust Cure Heavy Duty. I have used this a while ago when I slapped a single coat on without care to see what it does. I posted a little video on my YouTube Channel (link here), “OnemanandhisMustang”, called “66 Mustang & Frost products I use”.  This was very much an experiment and I only put a single coat on. But the rust didn’t get any worse. So today I decided to try the Granville Rust Cure (Grc from now on), to see what it was like if I used it properly. Here goes:

Product Description:

Granville Rust Converter is the rust convertor used by the oil and marine industries, the MoD and NATO.

It is used to stop corrosion in environments far more severe than your car will ever see . . . and it WORKS.

Drying to a tough gloss black finish it can then be top coated with most paints.

Environmentally and ecologically safe. Acid and lead free. Non-flammable.

MUST be applied to rusted ferrous metals. Kills old rust and stops new forming.

Sounds impressive, but is it?

The Tub:

This comes in three sizes, the size I have here 250ml, 1 litre or 5 litres. With 5 ltr I expect you can dip the whole car in it. This stuff does seem to go a long way. The instructions say pour into a non metal container ans apply thin coats between certain temperatures.  There is also a reference to not store below freezing. Not sure what the temperature does to it but I store it in the house, much to the wife’s disgust.


I will use this treatment on the brake drum that I had previously taken off. The drum had a fair amount of surface rust on it so it was a perfect candidate. I lightly wire brushed off the loose rust ready for the application.

The first time I spread this on a rust patch it was full of bubbles when I applied it to the rear window channel. Why I don’t know, none of the other converters do it. In fact it annoys me, a lot. Other’s are very watery like and run off, that annoys me too, but no bubbles, grc is thicker so no run off.

This stuff looks like milk and spreads like a watery single cream. The back of the pot advises to stir lightly, I guess that is so you don’t fill it with air. I poured a little in a plastic take out container. The instructions advise to lightly dampen the surface in order to help adhesion.

A small brush was used to apply it. Almost immediately the white milk bubbles and starts to change colour to light blue. I quickly went all around the drum and applied a thin layer as recommended. The pot does not say anything else, but as this was an experiment I started to play. I started to go over it again, to smooth out the bubbles, this was looking good, it was starting to thicken fractions at a time.

All the time the colour was getting darker, the photos show the transitions, Grc dries to the touch in about ten minutes. I expect faster in warmer weather. I went over a third and fourth time. Now it was smooth. It dries to like a plastic type feel coating that is clear and turns the rusted parts black.

The second coat is recommended after twelve hours. (I shall do that and report tomorrow.)

Second Coat:

(I’m back, not that you would know I have been away!) I have taken some pictures of the first coat once the Grc had dried this morning. I then applied a second coat. This time I have taken a close up of the bubbles.  This time they seemed to disappear without to much hassle, the secret is this, as the mixture gets a little tacky just make sure you spread it around a bit more and make sure it’s not to thick.

Bonus time:

Bonus? Yep, this time I have taken a video of the rear drum from start to finish of the first coat. After that there is not much to see. So I have posted the video on YouTube under my channel “One man and his Mustang” under “Granville Rust Cure” or click here for the quick link, it’s worth a watch. If not only to see how my editing skills are coming along!


This is difficult – I can review the product how it goes on, and I don’t know if its any good at keeping the rust at bay. That will have to be a long term follow up. So how do I rate it. I can do a longish term comparison by the single application I applied to the rear window patch. By the fact it has not come back after a random slapping of it on there says something.  The fact it has bubbles and to get it smooth you have to keep re-brushing, that drove me nuts.  But 12 hours later I am pleased with the results so far. 7 hours after I video the drum I have checked it again, it’s now an almost matt black! It works, (for now).

Rating: 9 out 10

The application is a single step (for each coat). That alone is a major bonus. The fact it bubbles until it’s smoothed out is pain. But, I can put up with that if it works long term.  On the drums the bubble effect went away pretty much of its own accord, perhaps it was on rusted metal and not on paintwork had something to do with it. I can’t give it full marks until I know it will stop the rust. So for now, I can only rate on test patches and the drums as they are now.


The front drum has gone matt black, the second coat has seen to that. The rear drum first coat has gone a brown black in comparison. I’m pleased with it.

However, I am still not convinced how this will look on a painted side of the metal. I need to experiment on a little bit more.

*** Shocking Update September 2016 ***

It has been a few years 2013/2014 since I wrote my reviews on both of the products FE123 & Granville. I have kept the same test piece of metal out in the sun & snow as well as everything else in between. The metal was a splash guard from under a front fender which was left around the back of a shed. I decided to have a tidy up and get rid of it. Then I thought I would share the findings. To keep things fair I will post this at the bottom of all the tests for Granville & Rustbuster.

I am expecting a torrent of abuse over this because I haven’t done this or that. But the products say they convert it and protect it not me see their pitches below;

FE123 sales pitch

“fe-123 envelopes rust at a molecular level, developing into a neutral layer which exists between the steel’s surface and the atmosphere. This neutral layer prevents the migration of ions so that no chemical reaction can occur at the metal’s surface. Recent independent testing by ‘PRACTICAL CLASSICS’ magazine April 2011 proved that fe-123 not only converted the rust but also left a foundation that could be painted over without neutralising and came BEST IN TEST scoring ten out of a possiible ten ponts. If you would like a copy of the report you can down load from the top of this page. We where also awarded best in test by CLASSICS MONTHLY in there 2011 long term test results.”

Granville Rust Cure sales pitch

“Granville Rust Converter is the rust convertor used by the oil and marine industries, the MoD and NATO.

It is used to stop corrosion in environments far more severe than your car will ever see . . . and it WORKS. Drying to a tough gloss black finish it can then be top coated with most paints. Environmentally and ecologically safe. Acid and lead free. Non-flammable. MUST be applied to rusted ferrous metals. Kills old rust and stops new forming.”

  The update on both of these products is not looking good.  

I have not coated these converters with anything else at all since it was all done way back then. The results are there to see for yourself. It says on all these things it forms a barrier and coats to protect etc etc. I am not convinced let alone impressed.

You can look closely you will see the untreated areas are brown with rust and the straight edges. Rustcure is on the left, FE123 is on the right just before the white sticker.

Here is the test I compared myself click here or  I even done a few videos on the products on my YouTube channel click here or follow this link

You can see from that comparison exactly where I have added the products either side of a piece of electrical tape that i removed after application.

First Patch test
First Patch test

Here is a similar angle of the updated results:


The original second batch of tests

Second Patch test
Second Patch test

Again taken from a similar angle for the updated results:


The rest of the metal?



It’s clear to see that none of it has worked left uncovered or painted.


On the right there is a black piece of paint that I did at the same time out of my own curiosity, this has NOT rusted.


The black paint? That paint is POR15. The paint which was applied incorrectly with only one coat and not two like recommended, without treating the metal with their three step process, it has still outperformed the other two liquids.

The link for POR15:  or click here


Now you may say it’s unfair of a test etc. So I challenge Practical Classics magazine to show you, the internet or me their results after 3 years. Did they paint over it? I don’t know. However; neither was the POR15 and that didn’t rust in exactly the same conditions. I will let you make your own minds up.

For me there is only one cure for Rust – New metal!

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