ferny
Club Retro Rides Member
Posts: 982
Club RR Member Number: 13
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May 31, 2020 11:18:47 GMT
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The first picture is of the Herald. Five or six years ago I replaced both the rear wheel arch lips and threw some paint on. All paint then and now is Halfords car aerosol and only one side of the car has reacted. Each time paint goes on it appears to shrink? Even when cut back and fresh primer applied it reacts. Sometimes the primer will be fine in places and not others. Then the top coats will react in different places. It's very strange. I'm assuming the whole area needs going back to bare metal and starting again, but it also seems to randomly react in additional areas after that. This snap is after doing a quick tidy in one area and then blowing on extra primer to flat back the other day, so the reaction is still happening many years later. Is there anything which can be applied from a spray can like a stopper? I'm not after show scene quality, the paint on this car is just to keep the rust away.  The next photo is of the rear numberplate I'm refreshing. This morning I sprayed some extra lacquer on what was fractionally soft feom the night before and it was from the same spray can. It's developed this funky effect. I'm guessing it's reacted with the slightly soft lacquer and reactivated whilst half dead or something? But, it's only done it where there is base paint. The letters are vinyl and it hasn't reacted there. Any ideas? I'm just curious as it's going on anyway. The front plate didn't do this at all.  |
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Last Edit: May 31, 2020 11:21:30 GMT by ferny
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May 31, 2020 12:08:46 GMT
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Hi, there is a product called barcoat, its an isolator which should be used as a primer/sealer then when dry should allow you to add further primer or colour without further reactions. Ive used the upol branded spraygun type with success, however here is link to aerosol type for you, hope this helps. auto-paint.co.uk/aerosols/primer/400ml-barcoat-aerosol.html |
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May 31, 2020 12:18:17 GMT
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The first picture is of the Herald. Five or six years ago I replaced both the rear wheel arch lips and threw some paint on. All paint then and now is Halfords car aerosol and only one side of the car has reacted. Each time paint goes on it appears to shrink? Even when cut back and fresh primer applied it reacts. Sometimes the primer will be fine in places and not others. Then the top coats will react in different places. It's very strange. I'm assuming the whole area needs going back to bare metal and starting again, but it also seems to randomly react in additional areas after that. This snap is after doing a quick tidy in one area and then blowing on extra primer to flat back the other day, so the reaction is still happening many years later. Is there anything which can be applied from a spray can like a stopper? I'm not after show scene quality, the paint on this car is just to keep the rust away. The next photo is of the rear numberplate I'm refreshing. This morning I sprayed some extra lacquer on what was fractionally soft feom the night before and it was from the same spray can. It's developed this funky effect. I'm guessing it's reacted with the slightly soft lacquer and reactivated whilst half dead or something? But, it's only done it where there is base paint. The letters are vinyl and it hasn't reacted there. Any ideas? I'm just curious as it's going on anyway. The front plate didn't do this at all. on the Herald - If you flat out / fill the damage & prepare the panel to accept fresh paint then apply an paint isolator - this can be purchased either by the litre and sprayed on or you can purchase it in aerosol format - a link below of a suitable isolator / online stockist www.jawel.co.uk/index.php?main_page=advanced_search_result&search_in_description=1&keyword=isolatorOnce the isolator has cured you just need to lightly key the surface with something like P800's wet - don't rub through the isolator coat and if you do make good with reapplying isolator to that area - then you can apply your final paint finish to the prepared isolator - I'm very confident that this will resolve the paint reaction issues that you have been experiencing On the number plate - sometimes with paint there is no obvious reasons for the reaction but quite obviously one paint surface is working / reacting against the other or a surface contaminate on the paint substrate or within / upon the paint mixing / paint containers or even within the atmosphere that the part / panel / vehicle is painted within - any one undertaking automotive painting should keep a few things in the paint store: Spirt / panel wipe - all panels / areas to be painted should be washed down with this using clean / unused lint free spirit wipe cloths - only do this with gloves on your hands (your skin carries natural oils which is easily transferred to the panels which then reacts with the fresh paint that you apply) All spray equipment should be spotlessly clean & tested prior to filling with paint If you have a workshop where silicones / waxes / lumps & bits of oily mechanical parts are just scattered about - you are going to struggle with paint adhesion / silicones / fish eyes in the paint etc - this additive in the below link may help if you have a few - but if lots start to appear then you best stopping painting - let the defective paint cure - flat it back & start again www.jawel.co.uk/index.php?main_page=advanced_search_result&search_in_description=1&keyword=fish+eyeYou need a dry well ventilated workshop - condensation or moisture in the air / dampness etc will result in spirit blisters occurring under the paint surface at a later date - incorrectly functioning moisture traps within the compressed air supply can also lead to significant problems I've been applying paint for several decades on vehicles and nothing ever surprises me - it's fraught with difficulty - to great degree there is a level of both science & skill - sometimes after all this experience it still baffles me - never beats me though - you just sometimes have to adapt to a different method The critical factors are preparation, good quality products, patience, cleanliness whilst remaining methodical and having the ability to walk away from it once the paint is applied and don't touch it until the paint has fully cured |
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Last Edit: May 31, 2020 12:23:28 GMT by Deleted
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ferny
Club Retro Rides Member
Posts: 982
Club RR Member Number: 13
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May 31, 2020 19:43:51 GMT
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Thanks for the detailed help guys. I'm normally fine with painting but I've reached a point where I need to stop fiddling with anything for a while as it's all going wrong! Idle hands and all that...
I've bought a can of barcoat instead of the aerosol and I'll use the airbrush I painted my alloys with. Having some in reserve seems wise.
On the plus side. A bit of research suggests I applied the lacquer to the numberplate too soon and too late. Despite it being uneven, I kinda like it on the car.
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I had a very similar reaction to the first one on My TR7, I think it was because around 8 years ago they moved to acrylic primer and I used the cellulose based topcoat I already had.
I'm fixing it now, I didn't fill them as they seem to be getting progressively worse so I flatted back to below the cracks and painted with an epoxy primer before re-topcoating in cellulose this seems to be working fine.
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hi, its happened in my garage twice, once which it called fried paint,rection and one from old paint reaction like yours.
the prosses is; dray sand the area till the cracked places disappeared, start with 600 grid, some time hard surfaces 600 not working use 320 or even 180 grid ,when these cracked or affected area cleared , smooth the area with 230 grid the apply BARCOAT one or 2 no matter, leave it till very dry depend on the weather ,in uk leave it at less 1 hour then apply direct 2x layer base coat( car paint).and that is it
i did this 2 times and its covered and works 100./..
if you think when you touch it looks too rough its ok ,but still you can sand it with 800 grid gently and must be dry ,never use wet sand or any water ,coz the area is effected by reaction already.
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Last Edit: Nov 1, 2022 13:11:25 GMT by Rich
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I've had the very same effect and it turned out to be a mixture of incompatible paint types. Eventually after trying everything imaginable the only way to overcome was to get back to bare metal and use one type of finish only.
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looks like the primer has not dried properly and shrunk when you put topcoat on !
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Rhyna had that problem when she was painting her motorbike.
Yes the panels are plastic.
It turned out to be whatever she was sold to wipe it down between coats was causing the problem.
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Vitesse 6 Saloon
Vitesse Mk2 Convertible
BMW R1150GS
VW Amarok
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Most likely incompatible compounds as in solvent based paint will destroy water based paint etc. some paints are lethal I used enamel on my block the other week and the overspray hit some polystyrene, it melted!
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