Thread: Another OZ MK2 PDRacer build in Sydney "Wood Duck"

One of our friends keeps saying that I should suspend it from our ("cathedral") ceiling as an objet d'art ;). Funnily enough, I don't think she's joking!

I decided to copy the post of yesterday's work over to this page to continue showing off:

1. Hull: 1st coat le Tonk varnish, photo no. 1. Note the shiny, reflective nature of the finish :). Note also the opaque, refractive nature of the thicker patches of BoteCote :(





2. Hull: 1st coat le Tonk varnish, photo no. 2. Shiny :)





3. Hull: 1st coat le Tonk varnish, photo no. 3. Glossy :)





4. Hull: 1st coat le Tonk varnish, photo no. 4. More or less the same as photo no. 3 directly above





5. Hull: 1st coat le Tonk varnish, photo no. 5. Lots of lovely, even reflections :)





6. Hull: 1st coat le Tonk varnish, photo no. 6, featuring a nice shiny foredeck. Note the nice shiny glinting off the boom in the background :)





7. Hull: 1st coat le Tonk varnish, photo no. 7: another view of the shiny foredeck :)





8. Hull: 1st coat le Tonk varnish, photo no. 8. Reflets dans le vernis





9. Hull: 1st coat le Tonk varnish, photo no. 9. Photo taken without flash, to show up the shiny, glossy nature of the stuff on the side deck :)





10. Hull: 1st coat le Tonk varnish, photo no. 10: similar flash-less snap - lots of reflections in the smooth, shiny coat :)


Follow this link to my Flickr account, where there is currently great rejoicing, balloons and streamers. Well, great rejoicing, anyway ;).



You might guess - correctly - from the plethora of smilies scattered around the place in this post, that I am quite pleased with the result of the first coat of le Tonk on the hull. Extremely pleased, in fact. I will reserve an ecstatic reaction for later if I find that the bulk layer of varnish sets up and hardens adequately: something that I won't know for about 48 hours. It has started to show signs of losing its tackiness about five hours after application, so I'm hopeful of Good Things.

As I keep on saying, however, we'll see.

Looking good at the moment :))))).

Thinks of all the bumps and scratches that happened in the first three outings.... but thinks better of it. He lay low, and he say nothin'...

The same thought has crossed my mind too - but it looks nice at the moment...

Just on 24 hours after applying the first le Tonk coat on the hull, and it appears to be hardening off better than Goldspar was at that stage. I haven't tried the fingernail test on it yet, as it it is still far too green to contemplate that one. The signs at the moment are promising, but I'm not holding my breathe, having been severely bitten on past occasions. To possibly mix metaphors. Or something. One slight fly in the ointment may be almost literally that - small insects and baby spiders, as well as dust, are making their presence felt.

The fact that I am still hopeful and optimistic at this point is a good sign :).

Coat no. 2 (hull) may go on tomorrow, or maybe Wednesday - I'm not inclined to rush it.

I've hit A BIG SNAG :(. I very lightly dry-sanded to boom and decks down with black 280-grit wet-and-dry (Norton - I'd run out or the Wuerth "Sahara" at that grade) to remove the worst of the fluff and spiders, etc. This was followed up with a wipe-down with the supplied tack cloth.

Fortunately, I started off on the boom, so hadn't got very far: the varnish refused to flow over the boom's surface, leaving great gaping fish-eyes all over it. Once I realised what was going on, I chucked the brush in some turps, and wiped the boom clean with some turps-soaked paper towel.

I'm putting the problem down to the sandpaper being somehow contaminated with wax and/or silicone: the brush and varnish have had no different treatment than from before between the first boom coat and the first hull coat, and I employed a clean side of the same tack-cloth used previously. The only other difference was that I used one of the included 190 um paint filters to strain the varnish (blobs around the rim of the tin by now) - I would doubt that it was the culprit - but I wouldn't completely discount its being the problem.

Lucky I started on an easily-remedied surface: I've given the decks an initial swab-down with some meths, but I suspect that the damage might have been done. I'll clean the brush thoroughly with a few changes of solvent and wash it with soap and water after that - I may be able to salvage that (expensive) item. The varnish that I was using - fortunately, again, a smaller amount than last time - will have to be ditched, along with its conatiner.

I'll also soap-and-water the decks in the hope that I can dilute whatever contaminant I may have unwittingly transferred there: I'm glad that I didn't sand off anything else other than one of the (easily accessible) side air tanks.

Time to order some more Sahara...

This link here on sandpaper contamination gives much food for thought. Found at the top of a Google search.

The specific lubricant discussed is stearic acid, from the Greek for tallow, stéar. It's an 18-carbon straight-chain carboxylic - or fatty - acid. Norton uses this compound (or one or more of its salts and or esters, see Wikipedia link) as a lubricant in at least one of its papers (the "X3"). The author of the article in the top link ponders its effects on surface coatings.

This isn't to say that the sandpaper taht I used contained stearates, but the above information is suggestive. Wuerth don't call their "Arizona" and "Sahara" papers these names for nothing - it's because they are (almost) completely dry and contain no or very few lubricants at all. And hence have very little scope for contaminating sanded surfaces. I ordered another 10 metres of 240 grit from BoatCraft Pacific this arvo, and hopefully it will be here before the end of the week.

I really should have known better: I was a bit twitchy about using the sandpaper to begin with, but figured that as I'd taken the sheet from the middle of the stack things should have been OK. Wrong! Serves me right. The decks and boom will get a thorough scrubbing with soapy water (fatty acids again, ha ha) followed by lots of rinsing. I'll use dishwashing detergent as usual, rather than soap as such, of course.

If the washing doesn't work, I'm not sure what I will do...

Hi Alex,
Been watching your progress from the shadows, great stuff.

I am interested in your experiences with LeTonk, we have recently rebuilt our St Ayles Skiff after a breezy day last November bounced her on some rocks punching a few holes the hull.

Anyway, to come to the point, we used LeTonk to refinish the Thwarts and Gunnels and I had exactly the same fisheye experience on one of the Thwarts. The coat that went funny was simply a recoat after overnight drying, no sanding so no possibility of contamination.

So what the cause is I know not. But I find the fact that Brian M mentions the fisheye possibility in his literature interesting,sounds like something left out to please the Eurocrats. At the same time I found my tin was skinning overnight and getting rather 'bitty' so I filtered it with the approved filter, I also started adding a very small amount (5mls or less) of Gum Turpentine to the tin after decanting in the hope it would stop the skinning. It certainly helps, but more significantly I didn't get the fisheyes again (another 3 coats) so I wonder if the Gum Turps or something similar was the missing component.

It doesn't affect the gloss or (so far) the adhesion. I don't think I would mix mineral turps(white spirit) with it though. I found sandpaper less effective than the recommended scotchbright type scourer and plain water. Lovely self-levelling stuff, brushmarks are a thing of the past. Good luck with it, well worth persevering with for the end result.
Of course we won’t know just how tough it is until we have a full season under our belts but it does look like a refresher coat is going to be easy when needed.
Cheers
Chris

There is a recent/current thread on WBF re Le Tonk. I don't know that it answers any of your concerns but here is a link:

Le Tonkinois Update

Hi Chris,

Thanks for your kind words :). That's interesting. I started off with the scourer and got impatient (major fault of mine) with the slow progress and switched to the sandpaper. Funny thing is, the second coat went on fine over the (Sahara-sanded) first coat, no problems, nick and slick. It was the third coat going over the Norton-sanded surface that presented the nasty symptoms. So I'm inclined to blame the sandpaper at this stage. This afternoon is going to be spent washing the sanded areas down.

I am loathe to blame the varnish - at this point - as it is so easy and nice to apply and, as you say, beautifully self-levelling. And it seems to be setting up much better than Goldspar in my workswamp.

As to the gum turpentine, I can't believe that the Chemical Police(TM) would have banned that, as it is relatively benign compared with some of the things that they let through. But who knows what makes their minds tick. Thanks for the tip with the GT anyway, I will put it into practice :). I've got quite a lot of it as I use it in equal proportions with (extra virgin) olive oil and paraffin (baby) oil for cutting in lathe and mill (one of the several variants of the "Angel's Breath" recipe). I'll be very parsimonious with the stuff in any case.

Cheers,
Alex.

Hi Bob,

That thread started by our "very own" Compass Project :). Interesting comment about the silicone-containing tack-cloths. As I used the TC before both first and second boom coats I would be a bit chary of blaming it: but I was a lot heavier-handed with the TC before the third coat, so maybe...

If the tack-cloth does contain Si I shall be exceedingly annoyed. Better off making my own (and easily done with a bit of varnish and linseed oil(?)).

I might take the hint about the microfibre cloth and go back to using that; for some peculiarly daft reason (probably daftness) I'd completely forgotten that I've got a handful of 'em (albeit currently thoroughly dusty and in need of washing).

I must say that the Wooden Boat thread hasn't been at all reassuring, but I'll try Chris' idea regarding the gum turps before sharpening up the axe or getting out the blowtorch just yet.

Cheers,
Alex.

Alex the other interesting point was the hot on hot approach that is not possible with most varnish as it normally results is crazing.

Perhaps try a few build coats on the boom before touching it with anything else.

Mike, watching.....watching

I was finally able to look at the photos on Compass Project's Wooden Boat thread after some browser or network silliness: the beading looked exactly like what le Tonk was doing on my boom.

I've left the hull and boom air-drying overnight after washing and rinsing them what I hope is sufficiently. But if what people are saying on CP's thread, all the washing in the world is going to fix it as it appears to have been a problem in one of the batches of the stuff. If things go pear-shaped again, I will add a few drops of gum turps and try again. That may be the answer, but I want to try the unadulterated varnish first.

Fingers and toes crossed for tomorrow.

Hi Mike,

I may yet try the "hot-on-hot" approach, but the idea of drying/hardening times being prolonged sends me screaming into the scrub (see above ;).

Cheers,
Alex.

Right. I've just applied coat no. 3 (part 2) of le Tonk on the boom, after a trip to the hardware store to acquire a narrower brush from the same family as the other one that I'm currently using (Selley's "Ultra Smooth Finish" range). The latter made painting the stuff on a little more efficient. They are extremely nice brushes to use if the paint is behaving itself.

Which the paint appears - so far - to have done. It flowed one without grabbing, and hasn't pulled in on itself - yet. I will keep a close eye on it over the next four hours or so. Le Tonk appears to be back to its useful (for me) good self. There are faint signs of fish-eye dimples, so this statement is only provisional at this point.

Having said that, my current thoughts are still that it was contamination from the Norton wet-n-dry paper that caused the sudden apparent increase in le Tonk's surface tension. The paint was taken from the small 0.5 litre tin - the last of that tin in fact - and strained through a 190 um filter, same as the last coat. Got to try and keep at least a few of the variables constant between iterations ;).

Thanks to BoatCraft Pacific's and AustPost's fantastic efficiencies :))), the new batch of 240-grit Sahara paper turned up in the post this morning, so when the boom is dry I'll start on giving the decks and air-tank side that got the Norton treatment a reasonable sand followed by the usual dust-removing wash. This will hopefully remove any contaminants on these surfaces and allow for a streak-free surface on them. I'll be really interested to see how the unsanded and now-well-cured varnish takes to being overcoated by itself.

Quick page-real-estate-saving update: After 1.5 hours the coat is actually even smoother than it was when I applied it: not a sign of beading, fish-eyes or other surface-tension rupture visible.

More anon.