Bling Posted December 30, 2012 Share Posted December 30, 2012 I want to prep the underside of my car and the floor for painting. What is the best thing to use to rough it up a bit? I was thinking something along the lines of scotchbrite pads / some of those flexible sanding blocks you can get. Not much of it's flat, so I want to use something flexible. Suggestions? Surface is going to get prepped, then metal ready where needed, cleaned up, then por15 followed by a scuff and underseal. Quote Link to comment Share on other sites More sharing options...
Spencer Posted December 30, 2012 Share Posted December 30, 2012 How are you doing this up on axle stands? it is a cunt of a job. Scotch brite on the underside of a car wont help POR15 stick at all to other paints & old under seal. Under the car man I would just spot repair any rusty bits or where the under seal is cracked, kind of a waste of effort doing the whole thing in POR or proper paint unless you bare metal it, you will struggle for adhesion. Another option is to just spot repair then blast it with a sticky underdseal to get it looking nicer with less effort and hundreds of $$ or POR that wont stick The inside floor is a different story, you can easily prep the shit out of it and get adhesion, best bet is DA any big flat areas then hand sand. Personally I would probably bare metal any car I was keeping as 90% of the time the old seam sealant is hard and hiding rust. Or at least pick out all the seam sealant and sound deadening,remove rust, prep existing paint, epoxy/por15 etc then re-seam seal, top coat if you want to Quote Link to comment Share on other sites More sharing options...
Bling Posted December 30, 2012 Share Posted December 30, 2012 Ah, a bit more info. It's been stripped of 95% of the under seal on the underside. Only areas I haven't done are the inside of the guards. It's currently setup like this: http://iforce.co.nz/i/nevxnyvq.a3a.jpg I haven't bare metalled it however, but have it at this stage: http://iforce.co.nz/i/1t3btr2t.dfc.jpg I originally stripped it all back so I knew what I was looking at. It was dirty and the underseal was original and not in the best condition. I have a couple of big tins of underseal ready to roll lol. Rust wise, there is relatively little in the floor area. So my plan was to rough it up and basically seal both sides with paint. The top side would just be left as paint as will all be covered with carpet. The underside I wasn't sure if I should just do patches of por15 where it's bare metal and underseal the whole lot. Or por15 the whole underside, then underseal to add protection on top of that. Open to your ideas though. Bascially just want to protect it from the atmosphere as best I can. Rust wise there is piss all really (in the floor / underside) so I was just going to cut out what little there was, patch that, then coat the whole lot. If there is something else I should be painting on better suited, then i'm happy enough to change plans. Quote Link to comment Share on other sites More sharing options...
bubblegoose Posted December 31, 2012 Share Posted December 31, 2012 wire wheel rust bubbles and dig it in to all the seams where rust will hide. smash a good coat of brunox over the bare metal patches then the next day some sticky paint like hammerite or rust kill enamel give it a few weeks for that to set then get underseal happy. good idea to brush some into the seams the day before you paint the full underbody Quote Link to comment Share on other sites More sharing options...
Evan Posted January 1, 2013 Share Posted January 1, 2013 I did the underside of the rx7 in POR15. basically the back half of the car was patchy surface rust and front half was patchy underseal. the underseal chipped off easy as. the steel for the most part was smooth and still had that protective coating on it from when the shell is dipped at the factory. I did the car whilst it was on axle stands and its a prick of a job to clean the underside this way. I must have spent at least 40 hours under that car stripping, cleaning, and painting it. All i did for the prep work was scrape the old underseal off, use marine clean to clean the steel to where you could wipe your finger on it and your finger is clean afterwards. as i say it takes quite awhile to get it to this point (especially in all the hard to reach spots/corners of things etc). then just metal ready and paint. I plan on spraying underseal over top of it later for more durability Ive since attacked the paint with screwdrivers/hammers etc and it seem to have stuck pretty well, in saying this is did scrape a little amount of paint off the rails when the car beached itself the other day when I was putting it on the trailer - but i would imagine this would happen regardless of paint type used. Spencer - I thought you hate POR15 cos it didnt work for you? or did you just skimp on prep work oh ps I brushed the POR15 rather than spray it. pps. BZG that second pic you link shows reside left over from the underseal, all of that has to be removed Quote Link to comment Share on other sites More sharing options...
Bling Posted January 1, 2013 Share Posted January 1, 2013 Yeah the last bits are the 5% i've yet to sort. Solvents will likely remove that. Good to know both the above options work. Will get rid of that 5% and go from there. Did most of the work with it on a spit, but the quakes put me on edge so I took it off that and put it on a more solid base. Quote Link to comment Share on other sites More sharing options...
Testament Posted January 3, 2013 Share Posted January 3, 2013 I dont think he hates it, more just it's expensive and very finiky about prep which is often difficult or just a pita. some other products are 90% as good for less money and effort in some situations. that said prep for paint always requires effort for good results regardless of the product. basically por15 has it's place but its not the solution to everything. Quote Link to comment Share on other sites More sharing options...
Evan Posted January 3, 2013 Share Posted January 3, 2013 Fair call. Hate is probably the wrong word, dislike was more what I was meaning. As far as the $$ goes, The way I looked at it when I did mine was that I could prep/clean and POR then underseal (cost about $250-$300) or I could blast it, epoxy (or some other suitable sealant) it and underseal at a cost that would be greater than the POR15. I decided that even though the POR might not work and Id have to blast it afterwards, the chance was worth it (and it seems to have worked) basically I took the 'you dont know until you try' method, even if I wasted a couple of hundred $$ on it I'm not too worried. However you may like to take a different approach. Quote Link to comment Share on other sites More sharing options...
cletus Posted January 10, 2013 Share Posted January 10, 2013 I have 4 litres of satin black acrylic top coat for my ute, is this actually worth putting on if i paint it in a black epoxy primer like DP50? Quote Link to comment Share on other sites More sharing options...
Spencer Posted January 10, 2013 Share Posted January 10, 2013 Yup I would, Epoxy primers usually aren't that UV stable so can chalk up down the track. Is this long term paint or just a stop gap? Quote Link to comment Share on other sites More sharing options...
cletus Posted January 10, 2013 Share Posted January 10, 2013 long term. well as long as a cheap paint is going to last anyway. cheers Quote Link to comment Share on other sites More sharing options...
Spencer Posted January 10, 2013 Share Posted January 10, 2013 I would probably try go for a flat 2K top coat if its a long term thing, most paint shops suck at flattening 2k as they are scared to fuck it up and create a cloudy mess. But you can buy the flattening agent yourself and play chemist until you get it spot on. Don't let people tell you you cant flatten 2K either, its lies there are paint ranges of pre flattened 2k paint. I say use 2k as its about 1 million times more durable than acrylic lacquer, I have done a few acrylic satin/flat jobs and while looking great off the gun they always look abit crappy a couple years down the track. Quote Link to comment Share on other sites More sharing options...
LS 2 THE DEEE Posted January 10, 2013 Share Posted January 10, 2013 another option is using a matt clear, Ive used a spies hecker version which worked quite well it seemed a lot more durable than some of the other matt options Ive tried that can potentially mark quite easy Also heard of but havent tried putting hardener with basecoat I think it was at 5:1 an leaving that as a finished matt top coat. But would need to double check with the guy....he's got 25ish years in the biz and have seen some amazing work from him so dont usually question his methods lol Quote Link to comment Share on other sites More sharing options...
Spencer Posted January 10, 2013 Share Posted January 10, 2013 Yup you can flatten out your 2k clear also, as per the member nobumps Mercedes on here. He is the one that gave me the push to get my own flattening agent and mix my own 2k flat paint. I think using just base coat would very much depend on the brand you are using, some are not UV stable at all and will fail with no clear Quote Link to comment Share on other sites More sharing options...
bubblegoose Posted January 10, 2013 Share Posted January 10, 2013 some base coats like ppg deltron are formulated to have hardener added for use in places like engine bays to replicate the factory Durable but shit looking finish. as for flatting 2k i would always buy specialty flat paint over flatting it your self where possible ( ie with whites and blacks and some other common colours come in matt), matting base will weaken the 2k and make it transparrent making it scratch and mark easier than straight 2k, spies matt clear is by far the best in the normal range of paints and mipa 2k matt black is bloody amazing to use Quote Link to comment Share on other sites More sharing options...
yetchh Posted January 22, 2013 Share Posted January 22, 2013 Ok, so I'm looking at my zephyr and how sad the paint is, oxidised, bad job to start with etc etc.. how do I tell what sort of paint it is? I'm assuming its enamel based on how tough and old it is. Is it possibe to coat enamel with 2k? or does it need to be cut back.. red isn't the orginal colour either, earlier in it's life it was pepperment green but some bright spark decided red was better... maybe it wasn't fast enough... Quote Link to comment Share on other sites More sharing options...
Rookie Posted January 22, 2013 Share Posted January 22, 2013 I found out by sanding, Enamel clogs sand paper at warp speed and turns plastic like. And yea you should get rid of all the old paint before paint. Quote Link to comment Share on other sites More sharing options...
yetchh Posted January 24, 2013 Share Posted January 24, 2013 Dang.. I was hoping to not have to take it right back, is there no way a 2k primer would go over enamel? Quote Link to comment Share on other sites More sharing options...
Spencer Posted January 24, 2013 Share Posted January 24, 2013 Most epoxy primers say they will coat over enamel on the data sheets, but they allways say to test before encase of frying etc. If you want to keep the car for a long time and the old paint job is that shit I would delete it Quote Link to comment Share on other sites More sharing options...
bubblegoose Posted January 27, 2013 Share Posted January 27, 2013 If you want to keep the car for a long time and the old paint job is that shit I would delete it this^, new paint will only stick aswell as whats under it. But if you decide not to remove it all you can do your repair work as normal then before paint use a product like PPG DP4000 as a wet on wet primer sealer, and if you run out of time it can be painted over upto 5 days later without having to sand it back Quote Link to comment Share on other sites More sharing options...
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