adriantr4 Posted November 29 Report Posted November 29 (edited) Hello I have been working my way round my TR4 fixing the bodywork with filler and adding a couple of layers of primer as I get to each panel. It's been a lot of work. My process is to return to bare metal, add filler in the usual fashion, then an application of grey primer in a can followed by an application of grey high build primer in a can. This has worked well (I thought) until today when the high build effectively acted as a solvent and disturbed the lower layers. Yesterday afternoon I applied the high build, but when I checked today a number of "cracks" had appeared - mostly when I had put it on a bit too thickly. Undeterred, I sanded out the faults using grades of wet & dry. I then applied the high build, but this time without warming the can. There were runs instantly, and my attempt to wipe one produced a big smear. Other areas also started to dissolve. This isn't good.... The base primer on the metal is a simple auto primer, containing "dimethyl ether, xylene, acetone" and the high build upol primer contains "ethyl methyl ketone, fatty acids, c14-18 and c16-18 unsatd, maleated, maleic anhydride". Apologies for any misspellings, the text is minute. What's going on? Shall I just leave it for a week or so for it all to harden, or an I stuffed.... Regards, Adrian Edited November 29 by adriantr4 Typo Quote
trchris Posted November 29 Report Posted November 29 Hi Adrian It sounds like you have a reaction between primers, you will need to go back to bare metal and l would only use the filler primer make sure everything is wiped with degreaser. If you going to top coat do it the same day as the primer will absorb moisture . Chris Quote
Malbaby Posted November 29 Report Posted November 29 Hi Adrian, Yes you are stuffed 😉 Rattle can primers and fillers are not recommended....2 pack primer/fillers are the industry standard. You will receive a variety of advice and opinions. I use "Restofinish" which is a 2k polyprimer....One product from bare metal to top coat and can be applied in various thicknesses. Quote
jerrytr5 Posted December 1 Report Posted December 1 Rattle can spray has a lot of thinners in order for it to spray properly. If it doesn't flash off quickly the thinner may soften the layers below leading to the issue you have experienced. Try and spray a few very light 'dry' coats from a greater distance over the affected area and you may recover the situation. Obviously a warm environment will help. Jerry Quote
stuart Posted December 1 Report Posted December 1 I would start again, go back to bare then spray a couple of fine coats of this Bonda rust Leave to dry for a few days then prime and paint. as Gerry has remarked there is a lot of thinners in those paint aerosols so spray thinly allow plenty of time between coats. the first couple will hardly colour it but you`ll stand more chance of it not reacting. Stuart. Quote
adriantr4 Posted December 1 Author Report Posted December 1 Thanks to everyone, appreciated, particularly Stuart. I'm going to follow the good advice, take a deep breath and return the to the metal. That isn't an issue, but there is a lot of filler which I might well damage. But I can fix it all up. I understand that professionals would go from prepped metal to proper primer in one step, I was aiming to rust protect each panel as I slowly worked my way round. Well, back to the orbital sander ... Regards, Adrian Quote
adriantr4 Posted December 1 Author Report Posted December 1 Postscript: I put the chemical information for both types of my two cans (simple primer and upol high-build primer) into the Google AI engine, asking how the upol would react with the layer of simple primer. The good news is that I got coherent answers, and the bad is that the solvents in the upol are very aggressive. I then asked if leaving the simple primer layer to harden would help - it won't. Combining the two as I did is a very bad idea No so good for me, but amazing that it recognized all the chemical components. No guarantee that the AI is 100% correct, but very plausible. Adrian Quote
stuart Posted December 1 Report Posted December 1 24 minutes ago, adriantr4 said: Postscript: I put the chemical information for both types of my two cans (simple primer and upol high-build primer) into the Google AI engine, asking how the upol would react with the layer of simple primer. The good news is that I got coherent answers, and the bad is that the solvents in the upol are very aggressive. I then asked if leaving the simple primer layer to harden would help - it won't. Combining the two as I did is a very bad idea No so good for me, but amazing that it recognized all the chemical components. No guarantee that the AI is 100% correct, but very plausible. Adrian The different base chemicals in the different brands is always a problem and not just in aerosols. Ive known problems in commercial products sold to body shops having similar problems unless you stay with the same companies products. Its also why body shops wont take on paintwork jobs from people that have done their own prep as well. Stuart. Quote
Phil Read Posted December 1 Report Posted December 1 Some good advice here, but as a matter of interest how warm is your garage? Quote
adriantr4 Posted December 1 Author Report Posted December 1 (edited) 5 hours ago, Phil Read said: Some good advice here, but as a matter of interest how warm is your garage? Chilly.... (I know - very bad for painting). Also explains why I haven't had (much of) a problem until now, my previous efforts were in the summer to late autumn, so the aerosols could flash off faster. It's been a learning experience. Here's the forum link on to how to prime for paint properly: https://www.trforums.com/index.php?/topic/88100-e-coatingrustproofingpriming/ Thanks, Adrian Edited December 1 by adriantr4 Added forum link Quote
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