Nick S once sealed an accent line, in a video, of white cedar from the adjacent stain by covering the trim line with CA glue and masking the then sealed trim line area. 

Hi John, 

apologies as i have been traveling on business for the last week....so just checking in here on clc forum.

thanks for the call out...and for Mark N...for suggesting it.  

first, most of my stain techniques with sharp lines are related to adjacent strips.  so when i looked at your proposed picture, the ability to get a sharp line across a strip, while not impossible, is a bit more problematic and challenging.  that said, all of this is also subject to a bit of practice with scrap wood to ensure you get your technique down before going for it in a big way.

all that said, the technique at a high level is as follows:

• define the line between stain/not stain.  
• mask the side that the stain will be on with fine-line tape
• apply a coat of epoxy on the non stain side (grumpy mentioned CA glue above....but i have not tried it with CA fwiw)  i do not really try to 'soak' the wood, just a quick paint-like coat on the wood.
• after the epoxy cures, reverse and now mask the non-stain side of the line (mask over the area you just applied the epoxy).
• stain the exposed wood.  it's important (and here is where practice comes in) to not soak the wood close to the line as it may get pulled into the unstained wood if too much liquid is applied even if you have properly masked it.
• after the stain is dry (and before removing the fine-line tape), put a skim coat of epoxy over the stain so that it stays in place and will not lift and move when you eventually glass the surface.
• remove the fine-line tape and clean up any bit of stain that got on the wrong side with a razor/sandpaper while carefully protecting the stained side (you can retape the line on the stained side so you see where you need to clean up).

as i mentioned, practice makes perfect.  if i was staining across the grain, i might also slightly score the wood with a razor to help block the stain from quickly being pulled along the grain across the line....but again, practice and see how it work.  the hardest part in my book is not soaking the stain around the line and making that part of the stain blend with the broader stained areas   i would also mention that a step or two back also quickly makes minor imperfections disappear.

below are two samples of the results you can get with this technique:

.h

   Hspira,  I stained my boat as dark as the one in your second photo. Beautiful work you've done.  Have you had any issues with heat affecting the epoxy due to the dark color?  My boat is far from done but the potential problem I've created has been on my mind.

John, I have a lot of experience in fine woodworking. The described approach makes a lot of sense to me. The most important part is to test this on scrap several times before trying it on the boat.  I have seen stain creep through the grain under masked and sealed areas. It depends on the stain and the species of wood.  

Hi BrianCb, 

yes, heat was a problem when we first glassed the boat using MAS epoxy.  it got through the first seven years of its life with periodic repairs every season related to heat which caused the epoxy to blister.

a little over three years ago, with the help of Joey Schott, now running Turningpointboatworks, we pulled off all the old glass/epoxy and refinished the boat with S glass and, i am pretty sure, Systemthree Silvertip which claims to have superior heat resistence. 

since then, it has not had any heat damage like it had when first built.  but i still do remain careful to try not to leave it on the car-top in direct sunlight during the summer.

i sent a note out to joey and hope he will confirm the epoxy we used and any other notes.....but definitely... yes.... it was something we discussed extensively and made some changes when we refinished the boat.

h 

   see response above...

   Thanks for the info hspira

My boat is a Jimmy skiff, it will be on a trailer, and never on the roof of a car.  I wonder if any of your heat damage was sustained during normal boating activities when it wasn't on top of the car. 

My apologies to John for hijacking his thread. I did think of something though John. If you're not dead set on a natural wood accent, a painted or decal stripe would be easy to execute cleanly over your varnish.

Hi John. 

i did want to come back to the question of lines.  with a couple other ideas as you look to sort out what looks good.   briancb started the thought above.

two other approaches in addition to staining a clean line are pinstriping (automotive/marine class pinstriping) and putting an accent line of wood for the line across the strips.  the accent line, becuase there would be glue between it and the adjacent piece as well as the grain would be oriented differently, would not pull stain through the wood cells osmotically....which is why its hard to get a clean stain line if you get the wood too wet.

i would also experiment. as i mentioned above, with a score line with a razor (or even go so far as cutting the pieces at the line....as glueig them back together will also create a barrier to stain being conveyed across the line.

Briancb, joey got back to me and suggests he used west 205/207 but in his note he thinks it was the substitution of s glass for e glass that helped improve the performance of the boat relative to managing the heat.   as mentioned, the dark brown top side can get very hot particular a sunny, non-windy day during the summer on top of a car.  so the boat developed a lot of white flecking becuase the wood is expanding in the heat tugging/pulling the glass to failure producing white flecking.    the s-glass is signfiicantly stronger (30% more tensile strength).   the epoxy subsitution (MAS for WEST systems), as joey recalled, was more about consistency and reliability and his experience with various resin systems.   that said, when i look at the technical data sheets, MAS per the sheet appears to be more heat resistent than West Systems. And SilverTip appear to have the highest temperature stability of the three (which is why i thought we used Silvertip.

anyway, that's what i know.   i would not over-worry on this.   the first iteration of the boat lasted 7 years before i ended up re-doing it and it was strip built vs okoume plywood so there are other differences that all played together to give you the problem i described.   

h

   Thank you hspira

My boat does not have any glass on the horizontal surfaces, with the exception of the cockpit floor.  The floor will be painted white so that will be OK. So this may not be an issue for me.  Once the summer heat starts I can lay out a test panel in the sun and see what happens. I'm really hoping I don't need to paint the whole interior white. I didn't think of this issue when I decided to stain the boat dark.  To be honest I should have skipped the stain altogether. It has added so much complication to the build trying to protect it during construction, get fillets to match, etc.

agree...the heat problem i raised is really about the interaction of the wood, the glass and the epoxy and that the glass doesn't move at the same rate as the wood when subject to heat and the epoxy itself weakens in the heat.

so if no glass involved, i don't think this is going to be a problem at all.

h