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LandymanStefan



Member Since: 30 Aug 2017
Location: Surrey
Posts: 881
England 2001 Defender 90 Td5 SW Epsom Green
Paint Adhesion issues...
Painted my rear crossmember a couple of years ago, fully sanded back to bare metal then washed with a water based degreaser and left to dry for a couple of hot summer days. Just before painting I wiped down the crossmember with the some thinners the same as the paint. Roller painted it with corroless s primer the over coated it with black cellulose based paint. Looked great. A couple of months after I got NAS rear step and dinked the crossmember when fitting it. A big flake of paint and the primer came off. I took a scraper to it and all the paint on the crossmember fell off.

So I scraped and sanded the entire thing again, gave it a thorough wipe down with isopropanol to degrease to avoid any possible moisture contamination then a wipe down with thinners, then painted with corroless s primer and corroless glass re enforced top coat, again roller painted and all seemed well for a couple of years. Having just purchased a new wheel carrier I removed the nas step to fit it. On removing the step it pulled some of the paint off of the crossmember to reveal fresh steel in a couple of small flakes. Now it’s nothing to the extent of the first time and you can’t pick off the other paint around the edges but it would seem that whatever I’m doing wrong means the primer isn’t adhering to the chassis properly.

I was hoping to remove and repaint my rear axle this year and I really want some solid longevity from the paint. Could anyone shed some light on what is going wrong? In my mind I now feel like I want an etch primer for anything I paint next so I would be interested to know what paint everyone else is using or if it’s worth getting an etch primer?
Post #888826 3rd Mar 2021 2:47pm
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Dinnu



Member Since: 24 Dec 2019
Location: Lija
Posts: 3469
Malta 2012 Defender 90 Puma 2.2 CSW Santorini Black
I etch prime all parts/areas that I take to bare metal, whatever that metal is, steel, zinc or aluminium. Never had issues.
I always spray paint the primer/paint, as is the only way I can get an even coating.

As a side note, if you use wirebrush on an angle grinder or anything similar on steel, it tends to 'polish' the metal and makes it harder for any coating to adhere properly. 1988 90 Hard Top, 19J Diesel Turbo, Shire Blue - Restoration ongoing
2012 90 CSW, 2.2TDCI, Santorini Black
Post #888828 3rd Mar 2021 3:01pm
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LandymanStefan



Member Since: 30 Aug 2017
Location: Surrey
Posts: 881
England 2001 Defender 90 Td5 SW Epsom Green
Thanks Dinnu, what etch primer do you use?

I was aware of the wire brushing after the first failure I saw it somewhere so the second time I gave it a thorough scuffing with paper before paint.
Post #888832 3rd Mar 2021 3:06pm
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hank



Member Since: 12 Sep 2016
Location: South Wales
Posts: 2314
Wales 2007 Defender 110 Puma 2.4 DCPU Stornoway Grey
I've previously had good results with upol etch primer. I had decent results using a cheapo ebay special etch primer too.

A couple of years back I put some masking tape on my defender whilst marking something out then when I removed the tape it took a 25mm wide strip of paint off with it, exposing the primer! As you can imagine I was less than impressed Laughing

https://www.u-pol.com/uk/en-uk/product/upo...D-2e2j7T-g > 110 XS Double Cab
Post #888838 3rd Mar 2021 4:15pm
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Ianh



Member Since: 17 Sep 2018
Location: Essex
Posts: 2103
United Kingdom 
^^^^^^^^^^

+1 for upol acid etch #8
Post #888888 3rd Mar 2021 8:43pm
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Dinnu



Member Since: 24 Dec 2019
Location: Lija
Posts: 3469
Malta 2012 Defender 90 Puma 2.2 CSW Santorini Black
I use 2 part etch primer, that is mixed 1:1 with an activator. I personally find these to be more professional (and hope to give better result) than the ones that come in aerosol. Granted that you need a little compressor and a spray gun. Per weight it is also cheaper.
I need to check at the garage what brand it is...always buy it from the same shop, and pick it up from the shelves based on the colour and design of their label. I can say I have no complaints about its performance. I have been using the same brand for more than 20 years. I first used it back in 1994 after some cleaning some spots of oxidation on the aluminium panels. Those areas never corroded again... not same can be said where it was painted by Landrover. Big Cry
Recently this etch primer was locally out of stock, so I got another brand (which I know the name but will not mention). Was also 2 part, 1: with activator. I hope performance is ok.. it just lacked the opaqueness when applied, so was difficult to judge if I had good coverage or not. 1988 90 Hard Top, 19J Diesel Turbo, Shire Blue - Restoration ongoing
2012 90 CSW, 2.2TDCI, Santorini Black
Post #889021 4th Mar 2021 2:27pm
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LandymanStefan



Member Since: 30 Aug 2017
Location: Surrey
Posts: 881
England 2001 Defender 90 Td5 SW Epsom Green
Thanks for the tips.

Please let me know when you find out what the brand was. When you say 2 part is it the same as 2k paint where you need an oxygen fed mask or is a normal respirator ok?

Might go with the UPOL for touch ups and get the two part suff for big jobs for when i do the axles etc
Post #889028 4th Mar 2021 3:06pm
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Oakseywick



Member Since: 20 Dec 2014
Location: Cirencester
Posts: 1000
United Kingdom 2000 Defender 90 Td5 XS CSW Java Black
I too have had a similar thing happen with corroless paint but I think mine is more a case of not sand surface enough after wire wheeling old paint and burnished the metal which is not sticking to too also used the part too quickly and did not let it harden long enough. It was on a slider tow bar but it’s is holding up well on the majority of it. Andy
Defender 90
Defender 110 XS
Cupra 290
Post #889038 4th Mar 2021 4:01pm
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Dinnu



Member Since: 24 Dec 2019
Location: Lija
Posts: 3469
Malta 2012 Defender 90 Puma 2.2 CSW Santorini Black
I use this product on bare metal. I have no complaints. Have no affiliation whatsoever.

https://www.loggia.it/en/prodotto/wash-primer/ 1988 90 Hard Top, 19J Diesel Turbo, Shire Blue - Restoration ongoing
2012 90 CSW, 2.2TDCI, Santorini Black
Post #889245 5th Mar 2021 2:11pm
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Dinnu



Member Since: 24 Dec 2019
Location: Lija
Posts: 3469
Malta 2012 Defender 90 Puma 2.2 CSW Santorini Black
Owe, and for breathing protection, I use same mask as I use for 2K paints. It uses filters for organic vapours. Mind you, I am not a professional sprayer, and do it in a well ventilated area. Still it is a job that I do not look too forward to it when need doing, but usually I get pleasure from the end result. 1988 90 Hard Top, 19J Diesel Turbo, Shire Blue - Restoration ongoing
2012 90 CSW, 2.2TDCI, Santorini Black
Post #889246 5th Mar 2021 2:15pm
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