G'day from Australia!
My names Josh and I am currently planning to undertake a respray on my first car, a 1978 Chrysler Sigma Scorpion (A '78 Dodge Challenger or Plymouth Sapporo to those in the U.S). As this is my first large spray job (I have done a few panels in solid colour acrylic on an old Kingswood), I have been sure to ask plenty of questions of my local jobber and have done a fair bit of reading online. The problem I have come across is that everyone I speak to seems to have differing opinions.
My current plan is to sand the clear off and give the colour coat a good scuff rather than taking it back to bare metal. As this is going to be a home job urethane is a definite no no. That leaves the options of Acrylic Lacquer and Acrylic Enamel (No hardener). To further complicate things the original finish is metallic baked acrylic enamel with a clear coat sprayed over the top. I want to stay with the original colour so this will be my first time spraying metallics. I have a spare door I plan to use as a practice panel.
Based on what I have read Acrylic Lacquer is easy to spray and very forgiving to work with but is very soft so not suitable for a daily (Especially one that will see dirt roads). I have also read that it is not suitable to be sprayed over any enamels as it will cause them to lift. Also based on my reading, enamel is also easy to spray, is more durable than lacquer but takes a very long time to dry, especially without a hardener and is hard to get a clear for. I have also read that you can not clear it unless you have used a hardener. My other option is to do all the body work, paint those areas with a cheap paint and drive it around for a while (few years) until I can afford to get a professional 2 pack job done. At this stage I am leaning towards using enamel more specifically Protec 363 although the paint shop says the clear they sell for it is quite yellow.
Anyways, just wanted your opinions on what I want to do and ask a few questions. Also if you've got any tips you want to share that would be much appreciated. Is it true that lacquer will lift baked enamel? Some I have spoken to say yes, others say no. Can you use an enamel + clear with no hardener, provided you allow the enamel to properly cure?
Cheers, this forum has already been a very useful source of information.
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Well, welcome.... and I've reached out to few of your fellow countrymen for comments on this but this is our old "tech" generally from 30 to 40 years so I will just comment on a few things. Acrylic lacquers have such hot solvents that they will adversely react with traces of almost anything that is incompatible with them. Since I don't really know what the resin base system is in your baked lacquers I don't know if those solvents are "hot" enough to lift that stuff. You could just do some testing and find out..... So, again this is just my opinion, if you got lacquer I'd be headed to bare steel, then building my paint system up....
And yes, acrylic enamel is somewhat tougher than lacquer ( more like compliant not really harder) however lacquer is at least easy to repair, well, it always was in my old world....
And, bottom line, I just don't know enough about your clears to comment on that last paragraph.
Hopefully some other guys from down under will comment here....
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here's some opinions with the baked acrylic enamel you MIGHT get by with the lacquer using the first couple coats light as a sealer. you MIGHT use a regular sealer and get by. BUT most likely its not going to work any broken edges will almost certainly lift. its to much of a risk I wouldn't do it. your enamel should be just fine with no clear, it would sure be beneficial to use a hardener. clear over uncatalyzed enamel is very tricky you have to hit it at the right time. unless you have an uncatalyzed clear?
they say my name is Jay
Best thing to do in a situation like this is to test. Sand through an area, feathering out and exposing each layer, then apply a couple of good wet coats of your chosen paint. You'll see the edges fry up pretty quick if there's going to be a problem.
The other thing that is likely on a car that age is that some panels may have been resprayed and you don't know what with.
So, I'd recommend sanding back as far as you can, bare metal is ideal. Then put a couple of coats of epoxy over everything. This will work as both a sealer and rust preventative and gives a solid base to build on.
If you don't want to use isocyanate hardened paints then acrylic lacquer is quite a good alternative, certainly much better than enamel. I still use it almost daily and it is capable of outstanding finish quality with correct application and buffing. Apart from its susceptibility to thinners, acrylic is still a very good paint - just labour intensive and this was one of the primary reasons why the refinish industry moved to 2K paints. It is more durable than given credit for - not suffering from the delamination that 2K clears can suffer. For example, I have a 1984 Laser here at the shop which is only now just starting to show sun damage on the original sections.
My recommendation is to go with an acrylic lacquer over the epoxy. Sand back the original paint as far as you can and finish to P400. This will give plenty of grip without deep scratches that the epoxy may not fill. If the panels are straight then sand to P800 wet and lay your acrylic base coat in 2-3 light to medium coats, making sure that you allow plenty of flash off time. If you use a medium fast thinner like Multi-Midway then 20-30 minutes at 20C should be fine. For clear, use a slower thinner - PPG Dulon AAA is the only thinner that I'd use with acrylic clear.
For your basecoat I'd recommend Axalta (Dupont) L400. It's as good as Dulon and probably has better colour support. For clear, Axalta 380S is streets ahead of anything else. Mix 1:1 with AAA thinner and even use a touch of retarder if the weather is a bit warm. It will go on almost like a urethane clear.
The key with acrylics is light, but wet, coats and sticking to flash off times. You can go up to 5 coats of clear then cut and buff for a beautiful finish. 5 coats seems a lot, but remember that it's a low solids product so there will be less left there after the thinners evaporates.
There is no need to sand between coats if you watch your overspray. Never sand the final coat of base. You can sand (P1500 wet) after the 3rd coat of clear, but really not necessary and adds a lot of extra work. Gun should be at 150-200mm, not more, and with light wet coats runs are unlikely to be a problem. If you get runs then move faster, rather than moving the gun further away. Acrylic dries very fast so maintaining a wet edge is important.
Back in the day we used high pressure guns but you'll get better results and less waste with a Reduced Pressure gun. Don't use HVLP. Good choices for acrylic are the Star S4000 V3 Pro (not General series) with 1.4mm setup or the Devilbiss FLG5, again in 1.4mm. The Star is about $220 locally, Devilbiss around $175 from the UK (link here). Run the Star at 30psi, the Devilbiss a little less at 26-28psi.
Hope this helps.
So a quality lacquer finish will be durable enough for a daily? Keeping in mind that the car will be driving dirt roads. The spots we painted on Dad's Kingswood seem to be holding up alright, though they weren't painted that long ago. They were done in HiChem Motospray aka the worlds worst paint. So those early Lasers are painted in lacquer? They seem to hold up well around here, only losing some of their shine. I will be buying a new gun (Retiring Dad's Supercheap Auto Siphon Feed) and was recommended the Iwata AZ3 HTE ($195) by my local jobber. He also said that the Walcom Slim guns were good but cost a bit more. I have also read that a larger tip 1.8-2.0mm is better for acrylics. At a guess I would say that that a larger tip would be better for acrylics if you are experienced as it will allow you to paint quicker, but a smaller tipped gun should be better for someone like me who is pretty new at this. Am I correct in my thinking?
I don't believe that durability of an acrylic was ever an issue. Done properly and given reasonable care that finish will last as long as a urethane and the clear will never delaminate. When they do finally give up they just start crazing as the whole paint layer eventually dries out. Takes a very long time, though. As I mentioned above, the move to urethanes was largely driven by the reduced labour cost - less coats and, particularly for smash repairs, much less need for buffing.
The AZ3 HTE is a great gun. I have two and use them almost daily. However, fan size is quite a bit smaller than the others. For me, painting bars, this is a good thing since I waste much less paint, but for an overall respray the guns I mentioned above are a better choice, IMHO.
Acrylic paints are thin with low solids and high thinners content. Even a 1.0mm tip will atomise them very well. I've never understood the argument to use a bigger tip like 1.8mm. Axalta recommend, for their L400, 1.2 - 1.6mm, so my use of 1.4mm fits right in the middle of that range. Go too much bigger and while you may need less coats the risk of solvent pop increases enormously as the coat is so thick that the top skins before the bottom dries. With acrylic the key is more coats, not thicker coats.
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