Gel Coat Guns

Discussion in 'Downeast Boat General Discussion' started by RCLS2016, Sep 8, 2019.

  1. RCLS2016

    RCLS2016 Senior Member

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    Do any of you guys spray Gelcoat? I am getting set up to finish last years projects and have the whole cockpit area, Engine box, Dash & Wheel house to gelcoat. It seems like a lot to roll and or brush...
    -Is it worth it to spray it?
    -Has anyone ever used the G100 or G200 Spray guns?

    I have a really nice HVLP setup but am afraid to destroy it if I go the spray route...
    Thanks in advance
     
  2. goin4broke

    goin4broke Captain

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    The G100 and G200 are 3.0 used mostly for spraying molds with straight gel. There gravity fed straight to the nozzle and I don't know how well they do spraying at odd anes like a horizontal surface. All the videos I've seen show them being used at only one angle to the work.

    I have limited expierience with this. I have a 2.0 and 3.0 tip HVLP. The best way to spray gel is to add Duratec High Gloss. It acts as a thinner and does not required waxed or adding wax to the mix as it has curing agents in it.

    Follow the directions to the letter, there is only one ratio for the MEKP which is 2%. That makes the pot life relatively short so consider spraying in cooler, early morning or even nighttime temps. The Duratec additive is sold by LBI (local to me) or any nuber of other distributors and is on the pricey side at about $100 per gallon and you will mix it to gel at a 1:1 ratio.

    I would at minimum get a spare container for the gun just for putting acetone in it to spray through the gun between batches and plan on breaking the gun dpwn and thoroughly cleaning it after every second batch. I have a shitload of gel to do myself and as of right now haven't made up my mind how or what to do. Do some testing and decide for yourself. Good luck and post the results.
     
  3. Quik Fix 16

    Quik Fix 16 Senior Member

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    MEKP and gelcoats come in different mixes. There are different % MEKPs for hot and cold temperatures. Resin mix is usually set by the manufacturer for the area and time of year. Harbor Freight spray guns on sale for $10. I buy them 10 at a time. Get the gun with the 2.0 or 2.5 tip.
    I have cup guns [G100} and that is not what you want for this job.
     
    Last edited: Sep 9, 2019
  4. goin4broke

    goin4broke Captain

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    To be clear yes straight gel coat would require varying the MEPK ratio based on conditions. I was referring to the ratio needed when adding the Duratec.
     
  5. Quik Fix 16

    Quik Fix 16 Senior Member

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    You can vary the ratio somewhat. Ideally the ratio would be 1.5 %. vary between 1.25 and 1.75 is acceptable. If the weather is hotter or colder you would use a different MEKP formulation other than the standard, such as DDM-9. There are MEKP formulas that are made for different temperatures. Lay up in Alaska or South Florida. The mix percent should always be in the 1.25 to 1.75 range. Does it work mixing more or less, yes to a degree. Is it right, no.
    The DuraTec high gloss additive is exactly what it says. A high gloss additive and it is great. Use it if you want a high gloss. For decks we spray straight gelcoat and PVA over it or mix a flatting agent, non-skid and PVA. I avoid mixing wax because it clogs the cheap gun. I have a $600 Sata set up that does not get anywhere near gelcoat. Try the cheap gun, you will be surprised.
     
    Last edited: Sep 8, 2019
  6. Quik Fix 16

    Quik Fix 16 Senior Member

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    Just as a side note, when I use DuraTec, I mix 50% gelcoat, 25% duratec and 25% acetone. Only because thats the way I was taught 35 years ago and it seems to work for me. Times have changed and we know a lot more about fiberglassing now than we did then.
     
  7. RCLS2016

    RCLS2016 Senior Member

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    Thank you for the advise guys.
    Quick Fix I think will try the harbor freight guns. When you say straight Gelcoat I assume you mean with no wax? I am also not interested in a high gloss finish as I'll be doing the decks for the majority of the project. So if adding a flattening agent do I calculate mixing the MEKP based on gelcoat volume or with flattener added?
    Thanks again
     
  8. MikesMarine22

    MikesMarine22 Senior Member

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    I like using the 3m accuspray guns with the throw away tips and liners for gelcoat. Easy clean up and if it kicks too quick it is all disposable and just wipe the needle with some acetone.
     
  9. Keelboater

    Keelboater Captain

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    Do you still have to wet sand and buff afterwards if you use the DuraTec additive? Sounds as if you do not but I'm wondering about the actual "as sprayed" finish. Never heard of mixing this into the gelcoat before. For the fancy work it sounds great. Thanks for mentioning this.
     
  10. leaky

    leaky Captain

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    Pretty soon I'm going to be giving a couple things a shot w/ DuraTec and a roll & tip method. Anyone tried that?.... Got a couple spots where perfectly shiny is not really a requirement to begin with but more shiny and less roller pattern would be nice, and it's a method I know.

    On previous projects I managed to both do a shitty job and destroy 2 spray guns w/ gelcoat and I freakin hate the process of stepping through paper, not to mention I don't even own a buffer and am hoping to live my entire life without one :)..
     

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