david c Posted September 29, 2015 Report Share Posted September 29, 2015 (edited) Hello wise ones Started spraying the car yesterday after weeks of prep. filling, sanding and filling and sanding again and for the most part really happy with the results. In places even managed to get a straight from the gun gloss. but on one area the bonnet, it would be the bonnet wouldn't it, I have an area about 12" square where the paint has not worked. I initially thought that I had a condensation drip from the spray gun as I could push the offending blisters around with my finger tip. So using my loaf I decided to pop the blisters with a pin and try to squeeze the water out, simples, but was suprised to find no trapped water! Okay, no big problem sand down and spray again. Bug**r there they were again, bit a little bigger this time. Time for a nice cup of tea and a bit of thinking, when I went back in to the "spray booth" joy of joys 99% of the blisters has disappeared. Except one. So out with the pin again and this time I gave it a little wiggle, horror of horrors the paint lifted away..taking the primer with it! more probing and an area about 3" diameter came clean away. This called for more than another cup of tea, walk away lock up and call it a day! My questions are does any one have any idea why this may have happened, What is/ should be flash off time, I undrstand it is a bit dependent on paint thickness, temperature and probably a heap of other things. Have I put on too many coats too quickly / slowly? How long should I leave the good panels before rubbing down and polishing? Sorry to ramble on David Edited September 29, 2015 by david c Quote Link to post Share on other sites
Motorsport Mickey Posted September 29, 2015 Report Share Posted September 29, 2015 More information needed, what materials are you using to spray, cellulose, two pack etc. How has it been prepared ? stripped to steel ? primer type used etc. As much info as possible will help avoid blind guesses. Mick Richards Quote Link to post Share on other sites
Tom Boyd Posted September 29, 2015 Report Share Posted September 29, 2015 Just about to say the same as mick..... Need more info! Sounds like a reaction from an aggressive top coat (cellulose) to un cured primer Quote Link to post Share on other sites
Geko Posted September 29, 2015 Report Share Posted September 29, 2015 about the size of a greasy hand palm or piece of cloth right in the middle of the bonnet ? Quote Link to post Share on other sites
TriumphV8 Posted September 30, 2015 Report Share Posted September 30, 2015 Back to the topic: Besides the idea that this bad reaction of the paint will continue to work in future and make the gloss bad the quick remedy is to isolate what you have completely with an special isolating primer and continue on that base. As we oldtimer freaks do not count the work hours and the labour and do not get paid for that I would heat the bonnet to get paint hard and grind it off and start all over again with a 2K primer and filler. That is the best way to sleep well in future because those imperfections can rise after years when car is supposed to hot sun as I had several times at Mille Miglia or later in summer in Italy. Quote Link to post Share on other sites
RogerH Posted September 30, 2015 Report Share Posted September 30, 2015 Hi Tom/Neil (and Nick - I couldn't remove your quote), I have deleted your posts as this forum is not the place for personal attacks. I do not know the history but don't bring it on here. Please please keep to your technical expertise which we all appreciate. Roger Quote Link to post Share on other sites
Tom Boyd Posted September 30, 2015 Report Share Posted September 30, 2015 Thanks Roger, If only i knew the issue........... Will be kept on topic as far as i am concerned Tom Quote Link to post Share on other sites
nigethomas Posted September 30, 2015 Report Share Posted September 30, 2015 Hi David I spent about 16 years in the vehicle refinishing game it sounds like you need to strip paint off the panel back to metal and start again.Check over any repaired areas etc and apply a sealer primer.To be honest though a good two pack primer does the job. Must make sure conditions are dry when painting and no water is entering spray gun from compressor.Apply one light coat followed by two heavy leave about 5-10 mins between coats.Also leave the primer to settle for several weeks longer the better Regards Nigel Quote Link to post Share on other sites
RogerH Posted September 30, 2015 Report Share Posted September 30, 2015 Hi Nigel, I did a simple aerosol touch up to my 4A bonnet. Applied the primer followed by the top coat. Over the next few months the paint finish (which looked good at the time) slowly morphed into this crocodile texture. It looks really good but probably better on a handbag rather than the bonnet. Roger Quote Link to post Share on other sites
nigethomas Posted September 30, 2015 Report Share Posted September 30, 2015 Lol crocodile finish like it ???? Quote Link to post Share on other sites
Graham Harris Posted September 30, 2015 Report Share Posted September 30, 2015 It could be silicon which is a painters nightmare or it could be paint Bloom which usually occurs on a bonnet or upper panel when you try to paint when the panels are too cold. The air from the spray gun creates condensation on the surface under the paint making the finish look cloudy. Sometimes you can get away with it but usually you will have to rub it back and paint again. Graham Quote Link to post Share on other sites
Guest ntc Posted September 30, 2015 Report Share Posted September 30, 2015 Roger/Tom There is no issues , My mistake for which I apologize ,I just thought Tom having experience with this should have shed more light on it to help the chap out. Quote Link to post Share on other sites
RogerH Posted September 30, 2015 Report Share Posted September 30, 2015 Thank you Neil and Tom, the world is too horrid to not enjoy what we have. Roger Quote Link to post Share on other sites
Motorsport Mickey Posted September 30, 2015 Report Share Posted September 30, 2015 I think we've frightened David off, no response since his initial post, doesn't look like it's urgent. Mick Richards Quote Link to post Share on other sites
david c Posted September 30, 2015 Author Report Share Posted September 30, 2015 Hi Guys (a unisex term I understand) Very sorry for not replying sooner, not easy to get the waves through to the garage at the best of times today was not the best of times! Being an amateur I am using cellulose, (was a printer and know the affects of isocyanate, scary stuff without the right gear). I used a good quality compatible self etching primer. I think perhaps I was just feeling sorry for my self yesterday. Back to work on the car this morning and after tentative poking about even more paint came off so bit the bullet and took a small steel filler spreader to it, slid it under the paint and primer, came off a treat. an area about 18" sq.and shaped in my mind like Cyprus! Could not for the life of me shift the paint outside the affected area so sanded / feathered the edges a good 2" back from the clean shiny metal using a selection of grades of sand paper and those cleaver abrasive sponge things. Took hours but as stated it's my time and it costs me nothing. Another lovely sunny day here in tropical Essex helped to harden things off. Wiped the whole bonnet over with panel wipe and sprayed three coats of Bondarust on. wandered off for lunch leaving the bonnet to bask in the midday sun for a few hours. Replete and refreshed back to the grind. Feathered out the edges some more and then some more again. Wiped over with panel wipe ( it actually took of some of the over spayed Bondarust, which puzzled me a bit). Then sprayed over with a light coat of my undercoat ( a mix of white and French blue, all from Auto paints Brighton) let that dry and then hit it again with two more coats. All good so far so no blisters so thought it best to walk away and locked up for the night, will see what I have got in the morning, if all is well will sand back again and apply three coats of top coat, leave it a week and then sand back polish and admire my handy work.............. Thank you all very much for your help advise and support, I really do take notice and appreciate it. David Quote Link to post Share on other sites
stuart Posted October 1, 2015 Report Share Posted October 1, 2015 Sounds as if you may have inadvertently left a rag on the panel sometime contaminated with something (hence the odd shaped area that lifted off) Especially if you could easily lift the paint/primer off and back to bare. Stuart. Quote Link to post Share on other sites
stillp Posted October 1, 2015 Report Share Posted October 1, 2015 I'd leave it a few days to get really hard before applying the top coat. Pete Quote Link to post Share on other sites
david c Posted October 1, 2015 Author Report Share Posted October 1, 2015 Sounds horribly possible, It was a long time ago now. Still all sorted out now, could still use a little more feathering though, ain't it suprising how just a few coats of spray paint builds up like the Berlin wall in slanting sunlight. Another rub down tomorrow and I recon it'll pass muster. I have to agree with those who advised take it all off, it would have been quicker and simpler. Have found it easier to prop the bonnet then spray. I am using a LVLP spray gun and it's brilliant! Again thanks all for your help. David Quote Link to post Share on other sites
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