ajlelectronics
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The TDS should be consulted for preparation sanding grit. Lechler suggest 180 ish, then 320 for overcoating, both dry.
That was done with a 60grit flap wheelThat is polished rust. Apply rust proofer if you don't believe me, and watch it turn blue. Sanding through rust is hard work.
I did it with a 60grit flap wheel, im going to try with my die grinder 90 and grinder.What kit have you available?
Blasting is by far the best option, but is no small undertaking.
I did it on my Alfa 75 thread, if you want to see how it could be done with limited kit.
Next best option is a Bristle Blaster but they are even more expensive than a cheap grit blaster set up.
Needle guns are the next best tool.
I assume you used a rotary wire brush to clean the rust off but as said that is polishing the surface but it will take some of it off so well worth doing.
Take as much of the rust off with wire brushes, needle gun, grinder with flap discs etc. then sand with coarse paper to provide a key.
I'm not convinced of the miracle cures under epoxy as I've never seen one recommended by a paint manufacturer.
I think that advice needs to be taken carefully. Epoxy is one of the most rust tolerant paints but I remember the Jotun manual saying that the warranty is completely invalid if there's rust. The rust really ought to be removed.Jotamastic 90 can be applied over rust grades a and b and even grade c.
Yes exactly. I'm looking for something that will last around 5 years then I will probably be at the point where I can afford to strip the whole car have chassis blasted and id probably have it galvanised instead.well its true ..you can apply it over rust , just dont expect it to last like it would over sandblast clean steel
surely were all smart enough to realise perfect prep will make a far nicer job than painting over a bit of rust , but then not everyone has unlimited equipment so some of us have to make do and paint over the odd rough patch under a car
If you do a decent job, remove all the rust you can and then epoxy it, the work will outlive you. If you want the ultimate belt and braces, then galvanise and put epoxy over the top.Yes exactly. I'm looking for something that will last around 5 years then I will probably be at the point where I can afford to strip the whole car have chassis blasted and id probably have it galvanised instead.
That is not true, read the Tds.I think that advice needs to be taken carefully. Epoxy is one of the most rust tolerant paints but I remember the Jotun manual saying that the warranty is completely invalid if there's rust. The rust really ought to be removed.
I have read the manual and I'm aware of the rust tolerance, but the warranty is in a separate document. To me this is Jotun saying, yes sure, use Epoxy on rust if you must, but be aware that if you do we can't promise any performance.That is not true, read the Tds.
it sets out what level of prep is acceptable.
You will get 5 years out of reasonable prep, probably 10
To me this is Jotun saying, yes sure, use Epoxy on rust if you must, but be aware that if you do we can't promise any performance.
Quick question on Jotun if I may......
Have bought some 87 with winter hardener to do some chassis components on the van and not massively impressed with the results so wondered if I am doing something wrong.
Trailing arms cleaned with a mix of abrasive wire brush, citric acid and media blasting then brush painted. Questions are:
1. The paint is really thick out of the tin, mixed1:4 with hardener its more gloopy than runny. Is this normal?
2. If I thin it using the Jotun thinner then when it dries, it dries mat, ie. looses the gloss finish. Is this normal? @Dcal I know you have said you thin it a fair bit to spray - does it still give you a gloss finish? (the finish in the pics is the 2nd coat which I didn't thin)
3. I put on two coats within 24 hours and have left to dry for a week. I am finding it is really easy to scratch the paint, it isn't "soft" but it almost feels soft, as soon as anything scratches it or knocks it the paint damages or chips. I have used Lechler before and it has gone off much much harder.
I'm not worried about the finish so am not sanding or buffing or anything just wanted a hard finish for underneath the van. A couple of pics just to show what I am doing
View attachment 298771View attachment 298772
Cheers,
MM
Thanks all, gave both tins a pretty good stir then mixed in a pot and stirred thoroughly so reckon it should be mixed ok. Also was using proper graduated paint mixing pots that I had from when I was spraying so ratios should be ok
Didn't realise it would be mat finish so that's cool, don't really mind for chassis components anyway.
Surface prep was pretty good, no loose rust or anything and I would have thought the media blasting would have given a pretty good key. This is what it looked like before painting - different shades are just the lighting when I took the pics.
View attachment 298901
It maybe that it went on too thick and so is prone to chipping...... next time I will try thinning it a bit as per Dcal suggestion and see how it goes.
Didn't realise how far 5l goes - got an awefull lot to use up
Cheers,
MM