REPAINTING SYSTEM DILEMMAs.

Discussion in 'Restorations' started by martinvention, Mar 4, 2018.

  1. As winter has stalled my Restro of Lottie slightly. I have been studying paint types and am in a bit of a quandary. So far all the panel-work repairs and running gear refurbishment has been preserved with Bonda and in the case of the underside also Rustoleum. Now I want to progress with a durable topcoat for the running gear and choose a system to spray the whole body inside and out. Thoughts so far:
    1. I do not want to outsource any of this fun/work, I have sprayed several vehicles before and have a good compressor + Devilbiss gun and large garage to make a spray booth and am looking forward to it.
    2. I do not want to use anything with Isocyanates, not just for my sake but the cat/neighbours etc.
    3. The bottom 500mm of Lottie all round was bad but above that there are lots of good straight panels and sound 1979 factory conditions finish, stripping that to bare metal would be a backward step.
    4. Epoxy Mastic seems attractive especially for the running gear but I get the impression it is not designed for air spraying which uses moderate pressure and relies on the paint flowing. Airless spraying at high pressure to mechanically build a solid surface seems to be the manufacturers recommendation.
    5. Epoxy primer seems attractive for the bodywork as it will provide durability, a measure of rust proofing for the inevitable tiny pits what will be there, a bar-coat between what is below and whatever the topcoat is. But the data and reports of its use when sprayed with an air gun are inconsistent.
    6. Non Iso topcoat options seem to be Cellulose or possibly Jawel non iso 2K

    I would be very grateful for any thoughts and views and recommendations for particular products.
    Martin
     
  2. JamesLey

    JamesLey Sponsor

    I’ve been spraying epoxy mastic quite extensively on our van and seem to get nice results on the underside and running gear. It needs thinning to get it to flow nicely.
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  3. Moo

    Moo

    The big problem with the isocyanate 2k is that it has an accumulative build up effect in your lungs if you're regularly exposed to it. I know a lot of people sing on about cyanide and how their neighbours pet dog took one sniff of the tin and dropped down dead, but that's tosh (im not saying these cases never happened, but im im saying there must have been an underlying problem beside the paint). If you keep your garage well ventilated, don't allow your cat in whilst/straight after you paint, and your neighbour isn't standing there watching you with nothing more than a hankie to protect him from the fumes, then the overall negative aspects are pretty much the same as, say, celly. Except 2k can be more of a bugger for attracting dirt and flies. All paint being sprayed and ventilated right out the door runs the risk of getting overspray on your neighbours nightie as it dries, or their car (or yours), or inquisitive cats.
    I haven't tried the jewel non iso 2k, so cant comment on that. Their standard 2k is a pretty good budget paint and you can use their super fast hardener for a quick dry time.
    Another good system, I've found, is the Glasurit 68 line - it goes on in a ratio of 4:1:1, covers really well, and, once you've got your painting technique sussed, will get good coverage from one and a half coats (light coat followed immediately by a second heavy coat). It's good, hard wearing, and quick (less hours of fuming the neighbourhood).
    Celly is good for home use, but it needs many more coats and it's imperative to let it flash off properly between coats so as not to trap the solvents which can lead to all manner of problems later on.
    Whatever you go for, you need a good cartridge mask as you'll be in the thick of it - for the cost, it's really not worth skimping on.

    And that's my tuppence. Have fun. :)
     
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  4. We used a letchler paint that's got a non isocyanate 2pack prmer to match....worked OK no show winner but more down to my lack of skills/equipment...
     
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  5. Gr8 post..:hattip:
     
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  6. Get Barry's mrs to pop round with her roller...:D
     
  7. If it's just the running gear you are doing i would use DTM ,direct to metal and needs no primer and goes on fantastic.I use it at work for hydraulic tanks and it's like granite once off.Its a 2k system s still has nasties in it.
     
  8. Many thanks James, Moo and all for the good advice rolling in. I will definitely use some good PPE and have more or less decided to use an epoxy primer. Thanks Deefer for comment re-non iso 2K, grateful for any more experiences especially using Jawel products.
     
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  9. Time to update following snow and days reading about paint on the internet. My perspective so far and this could be a running commentary as I have decisions yet to make. So please chip in and offer advice especially if I have got it wrong:
    Paint at the factory with dip tanks, heated vented booths with robot sprayers is not the same as "Refinishing Systems" where we lay folks need to start looking. Even then the refinishing industry is geared differently to our needs so we have to understand why. Professional refinishers need a quick turnaround and we typically do some panel work, need to protect it bit by bit over months/years before we are ready for all over painting. We are also less likely to be able to provide the controlled temperature/humidity/ventilation/environment that refinishers have. So to the choice of paint:
    1. Interim protection for the long panel-work phase must not be porous as are most primers (including etch primers) and as it is done in small stages and awkward places probably brush applied. So far I have relied upon Bonda primer with zinc. It sticks exceedingly well can be thinned with cellulose thinners and seems to keep the rust at bay overs years.
    2. Primers for the big spray. Unlike the refinishers who will quickly follow with topcoat, Epoxy product seem to be favored by us. There are 1K epoxy versions but they dry slow and are not as stable as 2K and not recommended. 2K Epoxy hardeners do not contain Isocyanates and they are a bit safer to spray or roller apply. 2K Epoxy is much less likely to react with existing paint and many of us will retain some VW factory applied finished and also Bonda where they are sound. When fully cured Epoxy is stable will not react with many topcoats. It is available in thicker formulations as Epoxy Mastic which is good protection for running gear and underneath can be left as the final coat. However Epoxy is not great with UV light and produces a powdery residue over time. Epoxy can be applied in several coats to act as primer/filler and allow rubbing down to provide a flat blemish free surface for the topcoat. It is worth noting that some Epoxy paints are not designed to be sprayed with conventional airguns whether gravity or suction cup. Many fora writers recommend Epoxy products designed for the marine/commercial transport/construction use, Jotun & HMG to name a couple and I don't doubt that some have managed good results by playing about with thinners content and gun settings. However I believe these are intended for airless spraying at high pressure (1500 PSI) to "mechanically" produce a solid skin rather than "flowing" as with traditional highly thinned air sprayed products. So I have followed the advice to use products intended for automotive air spraying and will be using Lechler Epoxy primer/hardener/thinners.
    3. Topcoat I am still undecided given my criteria at the top of the thread and much choose between Cellulose or a non Iso 2K such as Jawel or one from the commercial transport sector. My understanding so far is that the lack of isocyanates means slower drying, but as with cellulose the finish can be great with sufficient rubbing down/cutting and polishing. I assume the 2K non iso will still be harder than celly but there does seem to be some concern about the non iso 2K spraying nicely.

    More to follow but please do chip in.
     
    Last edited: Apr 4, 2018
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  10. Having decided on Bilt Hamber epoxy mastic for the underside running gear (no real UV issues) and Lechler Epoxy primer (LS29107)for the main body inside and out, I am looking at topcoats and discovered some points of note: Lechler recommend the 29107 be finished with their ISOLACK or ACRITOP (Polyurethane and Acrylic systems) but never mind the name both system hardeners contain isocyanates. A good source for data sheets is: coatit.co.uk/download and a good explanation of the refinishing dilemma can be found here: https://www.pcimag.com/articles/100...hnology-lengthens-pot-life-shortens-cure-time but this article and subsequent reading about Dow Paraloid products seem to indicate that they are good for primer and clear top coats but not colour coats.
    So the quest for a Non-iso 2K topcoat continues and many of the online fora report poor results with the few offered (industrial and automotive). So I am swinging back towards Cellulose which I know and can be assured of a great result albeit not so tough as proper 2K. If I go down this route there is another question can Cellulose be finished with a non-iso clear coat? Any thoughts?
     
    Last edited: Apr 4, 2018
  11. JamesLey

    JamesLey Sponsor

    Bilt Hamber is great! I scuff it with 180-220 grit and top coat for our running gear and it came out great.
    I’m picking up some lechlar epoxy and high build next week. Our local place is doing a deal on high build so a good time to buy for me. Going with their top coat too so will let you know how that goes.


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  12. Chrisd

    Chrisd Supporter

    I was reading this and wondering what conclusions you reached for the bodywork primer and paint @martinvention and @JamesLey. I'm in a similar position with a non original paint job (not cellulose base and clear coat) needing patch repairs and so far unimpressed with non isocyanate rattle cans that call themselves 2k, but aren't and done hold up well.

    Do I go back to cellulose and apply a barrier to stop it reacting with the paint underneath or even go as far as bare metal or did you find a good non isocyanate solution?
     
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  13. JamesLey

    JamesLey Sponsor

    I can't really comment on a non iso solution as both the van and baja got painted with 2K. I've yet to have epoxy react to anything so I'd be tempted to try that as your barrier coat. Going back to bare metal is a lot of work.
     
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  14. Hi I agree with James the Epoxy part seems very stable and might be a good barrier coat if you go for cellulose. I don't have experience with with 2K and have been happy enough with Cellulose but it is not very durable over several years so use plenty and be prepared to cut back to a good shine. You can get good 'gloss from a gun' but need lots of thinners in last coats and and need to be watchful for running. Bare metal takes a lot of time and doubtless many repairs will be exposed and need re-filling and flatting. Whatever you do take plenty of time masking off, over spray gets everywhere and through the smallest gaps
     
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