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  1. #76
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    Hi Theodor,

    Ouch! What exact paint did you use over the PRi-COAT? Is the paint water-based? I'm no expert on surface coatings - I wish! - but it looks like an incompatibility to me - or something coming up through the undercoat (which doesn't seem likely). Hopefully someone with some actual knowledge(!) of such things can explain this! As another thought, did you use "wet and dry" sandpaper? Some (all?) of them contain lubricants (such as stearates) to prevent clogging, which do nasty things to stuff (paint, epoxy, etc) applied over it. This why I use "dry" painters' sandpaper off a roll.

    Have you tried looking at MIK's painting FAQ?

    Sorry that you're having this trouble.

    Cheers,
    Alex.

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  3. #77
    Join Date
    Feb 2008
    Location
    Eustis, FL, USA
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    It looks like the thinned second coat of primer has gassed out some solvent, affecting the topcoat. The only time you need to thin paint is on raw wood or other porous surfaces or when spraying and only enough to remove stipple.

    Norglass uses application specific thinners, though I'll bet they're just slightly modified spirits (maybe a slower flashing agent such as toluene), what thinner did your dad-inlaw use in the primer? I don't know of any adverse reactions with mineral spirits and toluene or any of the other obvious chemicals they might use in this primer (their spec sheet wasn't very helpful at all), but you've clearly got something going on and I'll bet it has something to do with the thinned primer coat.

    Generally, you don't need or want to fool with primers, again, unless you need to cut it, so it'll go through the gun, in which case only the recommend solvent should be used, unless you can identify the solvent cocktail employed.

    You know what's next I'm sure. Sand it back to the uncut layer of primer, add another coat of primer, wait until it's good and cured, then top coat. I'm not familiar with this primer, so I can't tell you how much of what might be in it, but it probably has the "usual suspects" in it. If the first coat went down thick, just knock it back with a light sanding. Also, I wouldn't recommend sanding primer with anything more then 220 grit, though 280 is safe, for the most part. Much finer grits and there's just not enough "tooth" for the top coat to grip. The finer grits are for top coats and once you're over 280, you're getting into the polsihing range, not sanding, which again is fine for top coats, but not a heavy bodied primer that has a bunch of solids in it (silica, bulking agents, etc.).

  4. #78
    Join Date
    Jul 2005
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    'Delaide, Australia
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    Thinners application can redissolve paibt itgoes over.

    I would just sand the affexted areaa ubtil you get good surface. wait a day or two. then patch the areas only then two coata in those areaa. with good sanding with a block to level the surface. after sanding dont apply next coat immediately but wait an additional day.

    somee varnishes behave like this if sanded then recoated with a thinned coat too.

    they randomly bubble the previous coat. but wait a day and they behave well.

    MIK

  5. #79
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    Jan 2009
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    Blaxland, Australia
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    Sounds like good advice, at least to an ignorant such as myself. PRi-COAT does need some fairly stern rolling-out to get it thin: it will respond to firm treatment and flatten out nicely, but, in my experience, you have to work it. It seems to be something of a high-build primer. Strangely, Norglass don't have an MSDS for it, but they do for their "Weatherfast Premium" undercoat: the MSDS for that reveals:

    UN number: 1263

    Constituents:
    Alky [sic.] Resin 28-35%
    Pigments & extenders various White Spirit 45-50%
    White Spirit 10-15%
    Additives various up to 100 %.

    Without the MSDS for PRi-COAT one can only guess at the components, and it would be silly to make any inferences based on the above - but it may be indicative, for example, the internal "thinners" might be "white spirit" (a.k.a "mineral turpentine" in some places). The PRi-COAT tin shows a UN number of 1263, same as the above; the Wikipedia lists UN 1263 as "Paint-related materials including paint, lacquer, enamel, stain, shellac solutions, varnish, polish, liquid filler, and liquid lacquer base, or paint related material including paint thinning, drying, removing, or reducing compound".

    None of my ramblings alter PAR's and MIK's advice above, of course.

  6. #80
    Join Date
    Oct 2007
    Location
    Sydney
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    Thanks for the advice. Today we scrapped away the areas where the paint had flaked then sanded the areas in order to take off the sharp layers of built up primer and paint.

    Unfortunately I have pretty much run out of Norglass primer. We were able to put some thinned primer down (I have been using the Hempel thinner, but only in very small quantities, hence we've run out). We'll assess the situation tomorrow arvo and then I'll have to try and find some suitable primer to use for a second coat.

    Its a learning exercise. Thanks again for the advice.

  7. #81
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    I wasn't drunk ... it was on my phone and the autocorrect had stopped for some reason

  8. #82
    Join Date
    Oct 2007
    Location
    Sydney
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    I have just about finished painting the hull of my OzRacer, thanks to the help offered by my father-in-law. I have set up the sail in the boom and yard. All that is left to do is varnish the inside of the boat, the centreboard, the rudder and tiller extension. I'd say I'm very close to finishing, except I know varnishing takes time to do reasonably well. I also need to organise a tow bar for my car and put into action a plan I have for using a friend's small trailer to carry the boat.

    It seems we've only had 3 weeks of warm weather in the past 2 months, but I am really looking forward to launching the boat. Once the paint dries today, I'll set up the boat on the lawn for my in-laws to see it before they head back to Oz.

    Now a question for Mik: is there an official OzRacer logo? I don't really have a name for the boat, so I have no plan to paint a name on the boat. The boat has never received an official PDR number either. Yet I did think it would be nice to have a logo of some sort on the boat to show it is an OzRacer MkII. To be honest, ducks don't really appeal to me, although I am sure some people would chuckle seeing a rubber duckie on the boat. Any thoughts?

  9. #83
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  10. #84
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    Sydney
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    Oh. That is very do-able.

    Thanks Mik.

  11. #85
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    I'd almost be tempted to black in the little arcs at the top and bottom so there is less cutting and the insignia is stronger.

    MIK

  12. #86
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    Oct 2007
    Location
    Sydney
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    I might fiddle with the graphic over the coming week to see if I can do what you suggest.

    I rigged the boat today to check everything. I need to figure how to bend my rudder box pin, seal the ends of all these lines, and remember how to tie all the fancy knots I used to know. Then I need some serious time for all the varnishing. Is it just me or does painting/varnishing taking as much if not more time than construction and epoxying?

  13. #87
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    Jul 2005
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    As long as you have the bolt through the tiller and the top front of the rudderbox I'm sure everything will work well.

    Take photos of the sail set at home and put them here - it is easy to do double check for how it is set up.

    MIK

  14. #88
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    Oct 2007
    Location
    Sydney
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    Well I have just returned from holidays, and while I have a few breaks from reading/writing this week, I hope to finish my OzRacer. Basically I only have the final anti-skid coat to finish on the interior deck and the logo/name detailing. Then it's a matter of finalising the rigging on the lawn. So its all so close!

    I have just been mucking around with the OzRacer logo. Here is what you suggest Mik (with top and bottom filled in):

    oz_logo_update01.JPG

    I am only using Microsoft Paint so it isn't anything special to look at i.e. the colours don't match but I'm not concerned for anything but a template for the boat.

    My suggestion would actually be to widen the slash which runs from top left to bottom right. Hence:

    oz_logo_update02.JPG

    Again this is a freehand edition using Paint, so the dimensions probably aren't accruate or completely athestically pleasing. This thicker slash keeps the Z in proportion - its my opinion.

    So Mik, will you make a definitive decision for an OzRacer logo or can I go with what pleases my eyes the most (i.e. second option)? I don't know how much demand you'll have for this logo in the future, but the engineer in me would appreciate knowing the standard before work commences.

    Cheers,
    Mark

  15. #89
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  16. #90
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    Oct 2007
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    Just a heads-up: I plan to launch my OzRacer on Saturday. I have finished all the preparations, took pics to clarify everything was set properly, but I am just too tired to load them onto Flickr and post. Tomorrow I have to finalise the trailer and mast holder. it looks like the weather may turn bad tomorrow, so I'll keep you all posted.

    I just don't want to look back at the dates when Koala and I first started on the foil blanks. I think it was something like 5+ years ago!

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