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Thread: Kayak DIY Paint Job - Can it be done well and last?

  1. #1
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    Default Kayak DIY Paint Job - Can it be done well and last?

    I did a brief scan of the forum to see if anyone has created a thread on DIY painted yaks and found none so.....

    From what I've read many have indicated that painting a yak, due to the rotomolded polyethylene material it is made from and its inability to bond well with a DIY paint job, results in a yak that will have its paint peel, chip and look like crap in a very short amount of time. What isn't really well discussed is the pre-treatment process that is necessary before painting a yak which is completely necessary for the polyethylene to adhere well to a new paint job.

    I purchased a used OT Twin Heron that is faded and scratched and since we're heading into the winter months, this seems like an interesting project to tackle. So I thought I'd shoot out a post of some of the information I've gathered to date to see everyone's thoughts.

    STEP 1: PREPARE YAK FOR PAINTING

    You'll need a "clean canvas" if you want to do an effective paint job so go about removing all of your yak accessories (seats, rod mounts, etc.) and then removing any decals from the surface. You can remove decals by sanding with some 220 grit sandpaper. You can also lightly sand areas of the yak that are scratched to help remove the scratches (there are other methods along the way of this process that will also remove any scratches (see below). It is advised that sanding should be done by hand rather than using a power sander. If your yak has significant damage on it (holes, deep gouges etc.) now would be the time to repair those. Repairing yak hulls has been discussed in many threads (plastic welding, epoxy-resin, etc) here at Snaggedlines and across the net so I won't go into that in this thread. Finally wash down your yak to remove dirt and sanding particles with soap and water (you can use some Dawn detergent if you'd like).

    STEP 2: PRETREATMENT

    First off, obviously painting plastics is a bit of a chore due to their general inability for paint to adhere to them. Their are multiple reasons why but the top two that I've found is:

    1. Polypropylene plastics have a release agent impregnated in them that will interfere with the adhesion of paint
    2. The molecular structure (polarity) of the plastic doesn't allow for adhesion

    So the first step would be pre-treatment of the boat to remove the release agent and change the molecular nature of the plastic to allow it to adhere to paint.

    This video provides a concise explanation of both of these processes and how to deal with them.


    There's a comment in the video above that I think does a good job explaning exactly why flame treating plastic helps new paint to adhere (outside of removing any release agents).

    from rickfischer51

    ... The reason paint doesn't stick to PE and PP is the chemical structure. There is no polarity, and the paint can't form any kind of bond. The flame treatment lightly burns the ends of the molecules causing them to oxidize. This creates polarity for the paint or adhesive to stick to. Corona discharge does the same thing. Home improvement stores sell PE and PVC shutters. The PVC shutters are paintable, the PE are not. the difference is that every fourth hydrogen atom in PE is replaced with a chlorine atom that provides polarity. Look at the rattle can plastics paints. They usually say use on all plastics except PP and PE. Easiest way to tell if you have PP or PE is put it in water. If it floats, it is PP or PE. Also, check the part for a recycling symbol.


    The flame treatment steps involve lightly flaming a small section of the plastic and then removing the release agent by wiping it off with a high percentage ethanol (OP used a 91% ethanol) with a cloth.

    STEP 3: REMOVE DUST/PARTICLES

    There are different ways to go about this. Some use a tack rag, some spray with an anti-static due to the nature of plastic to readily take on a static charge. However you go about it, you want to ensure as much dust/air particles are removed from the surface before you being to paint your yak.

    STEP 4: ADHESION PROMOTER

    Adhesion promoters (AP) provide an additional layer to the plastic you want to paint making the surface have a higher affinity/attraction to allow the paint to bond.

    There are numerous APs on the market and its important to use an AP that complements the plastic you are interested in painting.

    This video does an excellent job comparing the effectiveness of different pretreatments with different APs on a HDPE plastic object (hard hat):

    The scenarios he tested were
    1. No pretreatment; no AP; black paint base coating
    2. Flame pretreatment with scuffing (scotchbright pad); Bulldog AP; black paint base coating
    3. Flame pretreatment with scuffing (scotchbright pad); Plas-Stick AP; black paint base coating
    4. Scuff and Clean pretreatment; Bulldog AP; black paint base coating
    5. Scuff and Clean pretreatment; Plas-Stick AP; black paint base coating

    Finally he scored the hat at each treatment location using a cross-tick pattern with a knife and attempted to pull the paint off using packaging tape. The results are quite informative in showing which pretreatment/AP coating combination worked the best.

    Generally two coats (20 minutes wait between each coat) of AP are performed.

    STEP 5: PRIME

    I haven't found too much information about this, but priming is important for two reasons:
    1. Creates a prime color layer to allow your new yak color to pop when used. This is very important if you yak was originally colored a dark color and you want to make it a lighter color
    2. Fills in any light scratches or nicks to smooth the surface before adding the paint

    Generally two coats (20 minutes wait between each coat) of plastic primer are performed. Using a plastic primer with a flex additive is thought to create a more chip resistant paint coating.

    STEP 6: PAINTING THE YAK

    So I have yet to find a thread or a video of someone painting their yak and showing what it looks like 6 months/1 year/2 years after. Most just show you what it looks like just after the paint job which is not helpful. From what I can gather if you are going to paint your entire yak, the cheapest most professional way to go is to use an acrylic paint with a compressor. You'll need to do multiple coats and buying them by the can (like rustoleum/krylon) will become expensive. I'd also just stick with one color (at least on the hull of the yak) which will aid you in easily touching up paint issues that may occur in the future due to fading/chipping/scratches.

    I've seen many do stencil paint job (like this guy) to give their yak a personal touch, but again, I have no idea how well that holds up over time.

    There are also UV protectant clear coats (polyurethane type coatings) that you can put on after painting your yak which will help with color fading from the sun and also provide an additional layer of protection.

    You can also add decals to your yak if you'd like (good thread on that here).


    Thoughts, experiences, gripes, etc?

    Thanks,

    smithmal
    Last edited by smithmal; 11-01-2017 at 03:20 PM.
    2017 Native Ultimate 12 (Lagoon Blue)
    Bending Branches Angler Pro Plus Paddle

    2016 Old Town Twin Heron Tandem (Mango)

  2. #2
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    There is a wilderness systems pro that painted a pungo kayak. He states from start to finish he estimated the work to be between 50-60 hours. Just google painting a pungo kayak. You will find his article. I believe he gave a step by step instruction on it.


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  3. #3
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    Rule of thumb for poly kayaks.....1) if you want something to stick to plastic kayak, it wont. 2) if you dont want it to stick to your yak, you'll never get it off
    14.5 ft Sand colored Malibu X-Factor "the promise"
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    Plus 1 on the it won’t ever come off if you don’t want it on your boat...
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  5. #5
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    i know they're expensive, but vinyl wrap is the way to go!

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  6. #6
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    Yeah... I read that but thanks for the response. He pretty much did zero pre-treatment work, which from my reading is essential if you want to get any sort of strong bond between the paint and the plastic. Basically he sanded and then started spraying with rattle cans. Painting a kayak looks great for everyone until you get it out in the elements. What I'm interested is reviews from people who have custom painted their kayak after a year or so from the paint job. There is very little info/reviews/notes out there in that respect.

    smithmal
    2017 Native Ultimate 12 (Lagoon Blue)
    Bending Branches Angler Pro Plus Paddle

    2016 Old Town Twin Heron Tandem (Mango)

  7. #7
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    Thanks for the response. Man.... purchasing a vinyl covering to wrap my yak would basically be the same cost of getting a entirely new OT Twin Heron. From what I've read, a vinyl covering can last as long as 2 years. Is that what you've seen/heard/read?

    smithmal
    2017 Native Ultimate 12 (Lagoon Blue)
    Bending Branches Angler Pro Plus Paddle

    2016 Old Town Twin Heron Tandem (Mango)

  8. #8
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    Quote Originally Posted by smithmal View Post
    Yeah... I read that but thanks for the response. He pretty much did zero pre-treatment work, which from my reading is essential if you want to get any sort of strong bond between the paint and the plastic. Basically he sanded and then started spraying with rattle cans. Painting a kayak looks great for everyone until you get it out in the elements. What I'm interested is reviews from people who have custom painted their kayak after a year or so from the paint job. There is very little info/reviews/notes out there in that respect.

    smithmal
    look on the kayak hunting pages....tbose guys do lots of paint and use it hard. I bet they'll know
    14.5 ft Sand colored Malibu X-Factor "the promise"
    2010 Hobie Outback "the Gift Horse II"

  9. #9
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    Quote Originally Posted by kevinfry View Post
    look on the kayak hunting pages....tbose guys do lots of paint and use it hard. I bet they'll know
    hear is a good place to start

    https://www.facebook.com/groups/3382...oup_highlights
    14.5 ft Sand colored Malibu X-Factor "the promise"
    2010 Hobie Outback "the Gift Horse II"

  10. #10
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    Further discussion on paint adhesion to PE....

    Basically, from a molecular standpoint, PE is doesn't have very strong intermolecular forces on its surface and is basically inert and nonreactive. The trick is to add polar groups onto it's surface to make it more attractant to paint and allow strong adhesion.

    I was looking through this forum and a "coating chemist" indicated that there are basically two ways to add polar groups onto PE (in the world of chemists, PE material are known as "olefins":

    1. Through the burn technique noted above which will cause oxidation of the surface molecules allowing the surface to become polar
    2. Coating the plastic with a layer of chlorinated polyolefin (CPO) which is very much like PE except that it has polar groups on its surface (chlorine groups). A CPO that he suggested which should be solubilized in toulene or xylene is Eastman™ Chlorinated Polyolefin 343-1

    Another paint chemist that chimed in on this discussion indicated the following:
    Polyethylene and polypropylene are called polyolefins. The surface of this material is nothing other then hydrogen atoms. Basically there is nothing for the paint to associate with. By the way I am a paint chemist. The surface tension is low. Low surface tension makes the Teflon fry pan non stick. If the paint can not wet the material well it will not adhere. There are ways to paint this however. Everyone is tempted to take short cuts but they will fail. A Poly Olefin Primer may be applied. This is made of a Chlorinated Polyolefin produced by Eastman Kodak. It is only soluble in Toluene or Xylene. It is best applied at low solids 2-3% or 97% solvent. The applied film is very thin and the subsequent coating is put over this, The CPO sticks to the PP and the paint sticks to the CPO primer. Other ways are to flame treat or plasma treat. What this produces chemically , are carbonyl, hydroxyl, or carboxyl molecules on the surface of the treated material. These groups give the paint something it can sink its teeth into. These are methods that do work. What happen every time is the Mfg. produces a part and then decides to paint it. The molding material is the critical piece to the painting ? Simply said PE and PP are very difficult to adhere to. All due to the inert surface.

    Here's a similar product @ Amazon that comes pre-mixed in a spray can.

    smithmal
    2017 Native Ultimate 12 (Lagoon Blue)
    Bending Branches Angler Pro Plus Paddle

    2016 Old Town Twin Heron Tandem (Mango)

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