West Systems + Interlux Interstain?

Discussion in 'Wooden Boat Building and Restoration' started by nbehlman, Mar 15, 2015.

  1. nbehlman
    Joined: Aug 2011
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    nbehlman Junior Member

    Chris-craft style anyone about. And getting close to finishing time and I want to make sure I get this right. I am looking at the Interlux interstain, in Chris craft red. Here's a link:
    http://www.jamestowndistributors.com/userportal/product.do?process=checkout&part=2340

    I plan to apply west systems epoxy with the special clear hardener on top of that. In some places, I will use a lightweight fiberglass cloth as well. On the product page for the stain, it says "do not overcoat directly with unthinned epoxy." Ok, so I'll thin the epoxy. Is that good enough? Is there a better choice for the stain that is more compatible with epoxy?

    Here's my finishing plan overall:
    1.) sand and prep surface
    2.) apply Interlux interstain
    3.) apply west systems epoxy with special clear hardener
    4.) clean amino blush off of surface
    5.) apply epifanes varnish

    I want a Chris craft looking stain and I want the durability of epoxy. Is this a good plan? Is there a better way?
     
  2. pauloman
    Joined: Jun 2010
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    pauloman Epoxy Vendor

    why the epoxy? and if you do epoxy - why use a blushing epoxy that could really mess everything up.

    paul
    progressive epoxy polymers inc
     
  3. gonzo
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    gonzo Senior Member

    Thinning epoxy is a bad idea. If you need low viscosity, get an epoxy with low viscosity.
     
  4. nbehlman
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    nbehlman Junior Member

    I want to use epoxy for durability. I am using the special clear hardener. I assume there is still a residue that needs to be removed, just with not a visible blush.

    Can anyone recommend an alternative stain that might play better with epoxy?
     
  5. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    If stains are applied and allowed to dry sufficiently (a few days at least) the epoxy bond will be literally within 97% of a raw wood bond, so no worries there. It has to be a pure stain, not one of the stain/sealer products that have flooded the market in recent decades. These tend to block epoxy from getting a good grip on the wood fibers and a considerably reduced bond will result.

    Epoxy under varnish will not make the surface more durable, given the film thicknesses typical with bright finishes. Some level of hardness will be seen over the raw wood, but not enough to stop a dropped beer from leaving a dent (for example), so consider what you're adding to the mix. It's take as a fair bit of epoxy film thickness to appreciably improve a raw wood surface's hardness, stiffness and strength, much, much more than typical under bright finished surfaces.

    All this said, there are areas where an epoxy undercoat is desirable, but in most of these instances, you'll also employ a light finishing cloth too (4 ounce or less), for added durability to abrasion.
     
  6. OrcaSea
    Joined: Oct 2014
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    OrcaSea Senior Member

    I've looked into a similar process using epoxy as an underlaying substrate and it seems that some of the advantages are that you need substantially less coats of varnish for the same effect, and that when it is time to refinish it is easier to strip only the varnish down to the epoxy and reapply rather than down to base wood. That's what I have read, anyway, but it looks interesting.

    Also, I understand that well dried water-based stain is the best stain to use, and that some oil-based stains can cause adhesion issues. There is a heart-breaking series of videos on YT of a guy that had horrific issues with a wood dye under epoxy on his classic wooden boat that was so bad that it resulted in him having to actually paint that boat instead of the beautiful (and expensive) wood finish he worked so hard to achieve. Just to be safe I went with water-based stain on the mast & spar (and other future brightwork) and I'll let it dry a good month before applying any epoxy. I definitely intend on applying cloth to the base of the mast from where it slides down the deck hole (is there a nautical term for that?) into the step.

    West System worked up a stain-adhesion test chart here:

    http://www.westsystem.com/ss/epoxy-adhesion-over-stains/

    Here is a short video series from Boatworks Today on his process of applying epoxy/varnish over wood:


    https://www.youtube.com/watch?v=IqiXZrs5hvM

    I have a question: If varnish imparts an amber color to the finish, why would a water-clear special epoxy be needed?
     
  7. PAR
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    PAR Yacht Designer/Builder


    Even clear epoxy will add some color to a substrate and depending on film thickness, the color can be substantial, so special "clear" epoxies are formulated to cut down this color.

    If you need a really clear epoxy undercoat, don't use older goo and never hardener that comes out of a metal can. Older hardener will get a red tint and if it lives in a metal can, it'll develop this red tint much quicker. This is the color that will be added to the resin when applied. Simply put, call your epoxy supplier and see how old the formulation you'll use is. The fresher the better.

    The use of water based stains over oil is only a slightly better solution. Some oil stains can cause a reaction, but most issues can be traced back to surface prep and insufficient wait time, if there's bond issues. The guy on YT with the runabout troubles made several mistakes, some of which there was no recovery, other then complete surface removal and grinding back to clean substrate. Usually there's only a few options, if these types of mistakes are made and if you're unwilling to take the known steps to cure the issue(s), you're screwed and frankly it's your own fault, for being stubborn about the reality you're facing. Yeah, sometimes it sucks, like smearing around a bad batch of epoxy that doesn't kick off. You know what needs to be done and it's a gooie, sand paper eating, bad hair day, but there's no way around it, so . . .
     
  8. OrcaSea
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    OrcaSea Senior Member

    Yeah, goodness knows I've gone through a couple rolls of 80-grit...

    You're familiar with the mahogany runabout then? Very sad, I felt for the guy. After watching that series and communicating with him I took my mast (spar was new wood) down to the bare before conditioning and staining and they will live (& dry) on the rack for quite a while before moving on with finish.

    It's sad but true; some people's purpose in life is to serve as a warning to others :rolleyes:

    Covering the mast & spar won't be an issue, but I am still trying to work out in my mind the process for finishing the combing. I can't see any way of not finishing it in situ on the boat. It will be some sort of slab-sawn wood (I'm thinking Alaskan Cedar depending on how well it bends when cut thin as the front 180* will have to be laminated in a jig) with a shoe molding around the outside. Sanding any epoxy substrate on the molding will be difficult, but 8-10 coats of varnish will be equally difficult and time consuming if done in place. Off the boat is an option, but unless you plug in studs for mounting how would one touch up the finish where the plugs are?

    Just thinking out loud, but any experience in brightwork finish on combing would be appreciated.
     
  9. PAR
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    PAR Yacht Designer/Builder

    Bright finishes are mostly about technique and methods, rather than products. As most have figured out with my posts, I don't epoxy under bright work, unless I need to. It just adds to the complexity and maintenance. This is especially true of spars, which can take a beating in normal use. It's one thing to fix dings and scratches in varnish, but another to fix the underlying epoxy too, just because you thought it might be a good idea. There's a good argument for both approach, but I figure, no matter how much epoxy I use, it's still going to get beat up, increasing repair and maintenance difficulty. The only time I differ from this is if a cloth is also employed with the goo.

    There's no easy way to bright work. It's the brush consuming effort necessary and film thickness to insure durability, which has no work around. Spraying, removed pieces can speed things up, but it's still pain in the *** work. Alaskan cedar is one of the more difficult species to coat (with anything), but a good scrub with a 50/50 mix of toluene and acetone, prior to the initial coats will get most of the oils and tannins.
     
  10. pauloman
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    pauloman Epoxy Vendor

    all epoxy curing agents will yellow in UV and even in dark sealed containers. some epoxies yellow faster and more than other, but they all do it - it is the chemistry of epoxies. The color of the only nonhazmat epoxy curing agent is darker than spar varnish.

    varnish over epoxy is a good combination. The epoxy provides a stable no moisture base and the traditional spar varnish offers 'warmth', uv protection and an easy to maintain surface.

    Best base is a formulated' solvent thinned epoxy (vs homemake) using a high end cyclo-aliphatic epoxy (esp 155) - slight penetration, thin film etc. The spar varnish on top also provides mil thickness.

    for ultimate results a two part clear poly (LPU) on top of the organic varnish. Note that with only two exceptions that I know of, these clear 2 part polys (including the overpriced marine ones) do not contain uv blockers or absorbers. These 2 part polys (with uv products) can go directly over the epoxy base, but the varnish mid coat provides additional uv protection, mil thickness and warmth of color.

    paul
    progressive epoxy polymers inc
     
  11. OrcaSea
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    OrcaSea Senior Member

    Thanks, guys, some good food for thought here. I will let this stuff stew in its own juices in the back of my brain for a bit, but it sounds like there are places where an epoxy substrate might be worth the additional trouble and not in others. I'm thinking the floor slats would be worth epoxy & cloth, varnish on the mast (cloth on the base), and just varnish on the boom and coaming.

    Trying to epoxy the coaming while in place would be a major PITA, but a question that I have is, how much will a traditional varnish buildup protect non-moisture friendly woods? (Keep in mind mine is a small, trailered boat that will be garaged in the off-season).

    The reason I ask is that around the outside of the coaming the original design calls for an oak shoe base molding. When I stripped off the original combing & molding there were places where the Red Oak had literally turned to powder under the paint (this is a 50-year + boat that had never been stripped and refinished - only added layers of paint).

    I can't afford custom millwork and won't use unsustainable exotic woods. The off-the-shelf moldings around here are Red Oak and generic white wood (probably Hemlock or something like that) neither one of which like water at all. Will properly bedded & glued low-rot resistant woods with built up varnish encapsulation alone provide reasonable protection from occasional wetting on an otherwise well protected & stored boat?

    Also, Paul R., in your experience will clear Alaskan Cedar bend (15" radius)well for a laminate? I'm figuring 1/8" resawn laminates. I considered Alaskan because of it's weathering ability, perhaps Doug Fir would serve equally well? If there is a better alternative I would appreciate your thoughts?
     
  12. PAR
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    PAR Yacht Designer/Builder

    Alaskan cedar is praised for planking in some places, so I imagine it bends pretty well, though it's not the best species to have to finish. It laminates well. Douglas fir bends okay, though flat sawn areas will try to "bust out" on outside curves if severe. It too has finishing issues.
     

  13. OrcaSea
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    OrcaSea Senior Member

    Thanks, Paul.

    I've had pretty good experience, thus far, using a pre-stain conditioner. Some areas - especially mixes of very old and very new wood (like on my mast repair) - that I thought were going to be a problem, turned out much nicer than I would have thought.
     
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