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POR 15


Adrian
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I've changed my mind.

3  or so years ago I spent in excess of 100 hours stripping and prepping the underside and engine bay of the car. I FULLY prepped it as per the instructions prior to using POR15. Putting new brake lines on this week I noticed cracking of the body colour paint primarily on the chassis and delaminating from the POR15 (OK i thought, perhaps I didn't rough up the surface enough prior to top coating, so I ordered the POR15 bonding etch primer to allow a better key). I started cleaning it up this morning and lo and behold the POR15 coating is peeling away. I have done absolutely nothing wrong, have spent plenty of time prepping it, It just hasn't bonded to the metal, especially on the chassis and bodywork in the engine bay, presumably where there is excess heat and a bit of oil.

The only think I can think of is that the humidity in the uk is generally too high for ideal application. Nevertheless I would have expected SOME bonding to have occurred.

I suppose the only positive is, if it hasn't bonded I should be abler to peel it away in large strips.

I will however say the degreaser is the best I've seen, Metal prep is good and the engine and manifold paints are good. Just not looking forwar to repeating the many hours on my back - need a lift and workshop like Colins!

 

 

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Hello Adrian,

Have to say I've not heard of this occurring before and bearing in mind the hours you have clocked up it must be very disappointing.

Out of interest, when you cleaned the underside and before applying the first treatment of POR15 - the degreaser what was the underside surface looking like ??

I ask, because the one problem with POR15 is that it will not bond to clean surfaces; it has to have something to adhere to and that is usually the neutralised rusted surface.

Regards.

Richard.

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My experience with POR 15 is negative. It sticks extremely well to me, but rather less well to my cars and I have also experienced the “peeling off in great sheets” issue on my PI - just a few days after painting. I had even followed their instructions and used their (overpriced) prep chemicals. And yes, the left over paint will set in the can within a few days and the brushes are hard to clean.....

Strangely enough my son recently used up one of the small cans left over (I won’t ever use it on anything car related again) painting some garden structures straight onto rusty metal and it seems to have stuck really well. Ignore the instructions and don’t waste your money on the preparation stuff appears to be the way to go.  Or just buy a decent paint instead.

Nick

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3 minutes ago, Nick Jones said:

Strangely enough my son recently used up one of the small cans left over (I won’t ever use it on anything car related again) painting some garden structures straight onto rusty metal and it seems to have stuck really well

Hello Nick,

I think that is the critical requirement.

Conversely I have used Hammerite Kurust and when that has done its business then painted the POR15 - the result was perfect and never had a peeling issue. 

As you say, is their prep degreaser etc the way forward or a clever money making application ??

Regards.

Richard.

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it says it doesn't stick well to previous painted surfaces so I used wire wheel / flap disc to clean up. So not that rusty (in places) hence why i was careful to use the metal prep as the etch is supposed to provide a key on clean metal but some of the current flaking is also on the rusted surface.

The idea is it bonds with the metal/rust to exclude oxygen and hence prevent rust, it's done neither and I'm only lucky in the fact that my tears of dissappointment are running down my upturned face whilst lying under the car and not the paintwork.

An expensive mistake (although could be worse) so I'm in Nicks camp and keeping away from it in the future. Again I will say that the degreaser, etc appear to be very good, if expensive.

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  • 2 weeks later...

I stripped the old hammerite from under my bonnet and did the full por15 treatment. Time will tell whether it is good or bad. Like Adrian, a lot of time and effort possibly for nothing but more time and effort! I look on the good side though, at one point I was thinking about brush painting the whole car using their top-coat product.

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I've used POR-15 chassis paint on the outside of the fuel tank on my Scimitar GTE. The tank sits under the boot floor and gathers whatever the rear wheels throw its way, so a fairly exposed position.

I cleaned the surface with a wire brush then applied the POR metal prep solution before painting two coats of POR-15 chassis black. The paint is still in good condition after about 4 years and 10,000 miles, I'm happy with the result.

Nigel

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Several of the MG group I belong to are not too pleased with POR 15.  Based on several of the users, they are now getting keen on cleaning off the rust, a coat of Jenolite and then using Bonda.  I've not tried it yet but it's sitting there in anticipation.

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POR-15 works for me.  I have a test piece that I did over 10 years ago and have left outside in the sun and rain.  Used it extensively on the car and the only downside I have found (apart from setting in the can - use a plastic bag over the lid before refitting) is that it is not fully UV resistant - hence finishing with chassis black sorts it out.

c.

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I painted brand new uprights without using their primer/etch stuff, it peeled off. I used their primer/etch stuff and it’s spot on. The primer/etch stuff smells very much like Jenolite to me. It also leaves non-rusty/new metal slightly dull, similar to a light bead blast finish, much like Jenolite. 

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