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verhoevenc

Double dye stabilizing wood

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1 hour ago, verhoevenc said:

Images fixed. Thanks a lot photobucket for giving me that extra work...

Chris

Right? I've probably spent 15 hours so far over the last couple months replacing pics.

Bastards.

SR

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These look phenomenal. You could hang them as wall art, they look that interesting.

Glad to know the californiawoods people aren't ripping us off as it sounds very intensive.

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I've always wondered what it's like to drive a BMW around on a golf course whilst laughing and lighting a cigar with a hundred dollar bill too. Perhaps we can now ask.

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So it’s been awhile since I’ve goven some updates here. I’ve been keeping up with the process and been trying different things. One new thing I’ve learned is that the wood (think both species as well as figure type) highly affects the process. I’ll give you an example. That really densely eyed box elder you’ve seen a lot of pics of? Well it really seems to enjoy having short vacuum pulls of initial color (something I dismissed in earlier trials on buckeye burl) as opposed to long soaks. Here’s a great example where it had a 15-minute Edge-only vacuum of read (with usual 2x vacuum length soak), cured, then same with whole billet in purple, cured, sanded, then full multi-hour vacuum in final blue color. As you can see, all 3 colors are extremely well represented:

IMG_0273.thumb.jpg.d76e52f279d7c74d4737355ca2dd0341.jpg

Meanwhile, I then did a similar two-color process on some maple burl (less dense eyes) where green was my 15-minute vacuum pull and blue was my main... and as you can see the green is just incredibly overwhelming the blue! Still I nice look, but I would have never guessed, after working that box elder, that this maple burl would take so much green up in such a short time!

IMG_0272.jpg.fef79be481c51ca54b9825f768950db4.jpg

So yeah... it’ll be interesting to see if that trend holds true for other maple vs. box elder burl billets?

As a side note: I’m still dealing with warping issues at the time of resaw... very frustrating! Still no definitive answers. If I find a pattern around which do vs which don’t I’ll be sure to post it here.

Best,

Chris

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Ugh! WTH?! Why does PG suddenly have issues uploading photos directly from the iPhone??? Can the powers that be extend the allowed file extensions to include more image types? I’m getting errors about that every time I try to add pics via mobile.

Chris

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Update: I added the pics above... seems iPhones do hold them as jpegs... not sure why it won't work. Had to transfer them to my computer and then upload them. What a PITA.

Chris

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I'm unsure about the iPhone thing. Perhaps you are shooting in RAW or attempting to upload some other native format? Maybe it's a security layer preventing data egress? I don't use Apple products as a rule, so I can't imagine what it might be beyond this.

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Bummer about the warping issues. My thoughts on the infusion schedule for different woods is that knowing the tree from it being cut down to the workshop might be the only way to accurately estimate how varying pieces will react in the bag. For example, if the area the tree grew in was wet, you might find the takeup to be completely different to one from densely-wooded compact soils. This of course is based on the assumption that the resin is flowing through the same mechanisms that trees use to transport water, minerals and sugars. If it weren't for Ash being so porous as it stands, doing tests on "swamp" Ash versus a similar piece of hard-grown Ash might yield useful information.

How deeply can this go? I mean, can this be reduced to more of a science than pot luck or "art"? Can you read pieces and develop predictions on how it'll react under different infusion schedules?

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Ok, so with more experimentation I’ve learned some important things about the process; including ones about warping! Yay!

1- You CAN add too much dye. 3oz alumilite purple in one gallon CJ was too much. Apparently chemically you CAN go up to 4oz and it’ll still cure... but I found at 3oz it wasn’t mixing with all the dye and thus I had, as far as I can tell, free floating dye in the mix. I’ll be sticking to 2oz or less per gallon moving forward.

2- Stabilization is a bit of a misnomer! To someone like me that implies dimensional stability... wrong. Not sure how to articulate this but I’ll try: the stabilization process stabilized on a micro-scale, NOT a macro scale. So in the end you may have saturated cells with acrylic but that does not mean it’s not going to behave like wood still. And burl being burl it will move. Dimensional stability is NOT the outcome of the stabilization process, especially in very large pieces made from wonky material. But what that does mean, since it still behaves like wood, is that you can indeed wet it, weight-and-sticker it, and let it dry flat.

Best,

Chris

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2 makes the most sense to me also. I've been studying the science behind heat treatment of wood (torrefaction) and there's a definite level of assumption on what stability is and isn't in both subjects. Interesting that you can still manipulate the material in a wood-similar fashion. If wetting it has an effect, does that not mean it will also be affected by environmental moisture? I presume that the resin takes up the places that water might otherwise, but does that mean it also penetrates the cell walls?

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Ok, I’m retracting point #1 above. I no longer think the issue was due concentration as I’ve now seen the exact issue happening with much lower concentrations of dye (1.33oz/gallon). I’ll explain what I’m seeing and what I now believe is happening: I would see cured resin on the surface and foil after a few hours in the oven at the right temps and therefore pull it out under the manufacturer’s statement that the resin either cures or it doesn’t. Since I was seeing hardened resin it must be done curing then. It troubled me a bit that a decent amount of color would come off on my gloves though. I’d then go sand the piece and it’d look great... for a few minutes. At which point I would start to see dark pinpoints appear in the pores... these would grow, and then depending on how severe the issue they might even spread to connect with one another to darken the surface in areas. Same would happen when I’d resaw the pieces. A couple things that I found improved the situation with varying degrees of success:

1- vacuum cycle the piece again in another color or clear and cure. This worked well for some lesser cases. I also then re-tested that juice’s curing ability on pen blanks and it didn’t appear to negatively affect the juice.

2- washing the blanks thoroughly in water and then weighting and stickering them. This was a great learning experience for two reasons: firstly you could watch color come off these failed blanks so it really highlighted the issue well, and secondly this also taught me that a little water, weight, and time was all that’s needed to fix any warped pieces. Like I said above, it’s still wood! This washing process has an extremely high success rate!

But even though I have backup plans... it doesn’t mean I don’t want to get to the bottom of the issue! I was glad I had been taking absolutely minutiae-level detailed notes as I started noticing colder days, shorter cure cycles MAY be a factor... which would imply that this is a partial-cure issue... which apparently can’t happen. I now no longer believe that. I fully believe this is a partial-cure issue where the majority of the resin cures but some is left liquid that later seeps out. I might be wrong, but that’s my current thinking.

Someone suggested to me that my 55lbs of steel weights may be acting as a heat sink and causing my wood not to get as hot, as quickly, as the rest of my oven. So as always I went about making experiments to test the theory! Why I didn’t think of this before is beyond me and I’m embarrassed... but I got rid of the weights and simply used C clamps to clamp my plywood-and-stickers sandwich to keep everything flat and deter warping. DUH!!! I also placed my digital thermometer’s probe inside this sandwich against the billet’s surface (instead of just out in the oven), and then sat there watching in the cold.

Results: My thermometer doesn’t even read out anything under freezing... the oven dinged that it hit 200 degrees right as the probe first started registering! After an hour sitting there the probe was only reading about 140! It took 1:10 to finally reach the required 185 degrees to start curing... and that was only the surface of the wood! I can now easily imagine how 2.5, up to even 4, hours might not have been enough time to fully heat to the core of the wood with 55lbs of heat sink steel involved! I ended up keeping it in the oven at 200 for 5 hours and then a 3-hour blast at 250 for extra safety; which brings me too another point, I’m also not convinced that higher temps ‘drive out more of the resin during curing’ like the directions say it will, especially if it’s already had time to harden by the time you do your safety heat-blast. In the end this billet it looking great! There were almost no fumes coming from the oven exhaust when I was done (gunna watch more for that now as a potential indicator), almost no color came off on my gloves, the clamps kept everything nice and flat, and after sanding the surfaces and waiting over night I’m not seeing any weep issues! I know this is a sample of 1, and I haven’t resawn it yet, but I’m feeling pretty good about the result!

As always I’ll be back to be verbose as I learn more,

Chris

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If the clamps do the trick, excellent fix Chris. I was going to suggest pre-heating the steel, however that's a lot of excess energy consumption for no real gain.

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I tried the clamp sandwich and although it was MUCH better, it still wasn't perfect. I got one little spot on a blank that still had 'dye weep.' Granted, it was a part I was able to cut out on this over-sized blank so YAY! No losses there. However, this was enough to make me experiment further. Someone had said that, if I'm doing things right, the only time I should be afraid of warp is when I'm in the initial dry phases. If the blanks, after being dried, stay away from moisture then I should be fine in later stages without clamps/weights. I'm defining "away from moisture" as ONLY in the ziplock bags long enough for them to cool down, and at all other times either fully submerged in resin, or in the oven again.

With that in mind my process now looks like the below. I'm 3 blanks in with this process without a single hint of failure:

1- Use the sandwich-with-clamps method ONLY in the initial drying phase. Dry for minimum 48 hours, usually 60. Generally around 220-250 degrees

2- Cool in airtight ziplock bags only as long a necessary

3- Do standard soak or short-vac cycle

4- Cure standing upright on edge in oven for 8 hours at recommended temp (I use a C-clamp near a corner to ensure it stays standing up)

5- Do standard full vacuum cycle

6- Again cure 8 hours standing on edge

It seems that for the cure cycles there's still some negative consequences in using the sandwich. Maybe there wouldn't be in a better oven (convection maybe?), but for me that seemed to be part of the issue. I'm thinking that without adequate airflow through the sandwich it was hindering the blanks' ability to get fully up to temp... even with 8 hour cures. That or maybe the sandwich didn't allow for even distribution of heat and so some areas didn't stay at-temp long enough to perfect the cure (which I believe is 185 degrees for at least 10 minutes where there temp CANNOT fall back below 185).

So far this seems to be the best process. If that remains true this may be the final post. If not... I'll be back hahaha.

Chris

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I'm surprised that @StratsRdivine hasn't weighed in with his knowledge in this field, Chris. If there's one man who I am sure could troubleshoot the product, provide advice or simply tell you what you're seeing it's John.

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2 hours ago, Prostheta said:

I'm surprised that @StratsRdivine hasn't weighed in with his knowledge in this field, Chris. If there's one man who I am sure could troubleshoot the product, provide advice or simply tell you what you're seeing it's John.

Thanks Carl!  

Been up to my neck in carbon fiber work lately so not much chance to get on here, but is interesting timing.  Chris and I follow eah other on Instagram, so its kinda cool to meet up here and see what he's been working on.  Since most of my customers buying my CF are knifemakers, I run into a ton of guys stabilizing wood for knife scales, so its pretty common, but I never got into it, so my knowledge is quite basic.  But sometimes the basic is what we miss.  What I mean, is that few understand heat flow in thick substances - I am still learning, but in my job of heating glass, steel and carbon fiber in up to six inch laminations, I know that you have employ the great BBQ trick - low and slow.  In the case of a catalyzed resin, its possible to over heat the outside of a billet, hence cause premature crosslinking of the resin, thus sealing in liquid core resin inside, which has several potential outcomes.

I use several thermally triggered resins in my system, from vulcanized vinyl to mono-epoxy systems that cure at high temps, and one phenomenon I notice now and then if I heat too quickly is the vaporization of the crosslinking agent causing bubbling before it gets a chance to crosslink the resin.  Then it crosslinks, locking the bubbles in.  Another reason I go low and slow.  

What may relate better is my experience with epoxies and porous wood end grain.  The best adhesion I ever get is when I heat the raw wood with a heat gun causing off-gassing, and slight vacuum, then adding epoxy to the joint where the cooling process sucks up the epoxy, subsequently lowering its viscosity causing increased suck-in, then the heat starts to kick off and thicken the epoxy just in time to clamp and not starve the joint.   

Principle is likely the same in resin impreg wood.  Heat the wood to super dry, then while hot and under vacuum, infuse resin, then turn off vacuum, then do the reverse, and place under pressure to press in the resin.  Just my deductive reasoning, I have no idea how its done. I do know that casting Alumilite is similar, in that you vac out the bubbles initially, then let cure under pressure to smallify any remaining bubbles.  

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As always, it's humbling when anybody shares deep and valuable information others would jealously keep to themselves. This sounds like excellent information for Chris to add to his hands-on experience. As far as "still learning" goes, I think that a very over-used and likely misquoted piece applies; "once you stop learning you cease to be good". I'm truly grateful for knowing that I don't know, so at least I'm sort of ahead of the curve in a Dunning-Kruger way....

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Sadly you can't use the heat-wood-then-use-resin trick on these stabilizing resins. They have one property that kind of ruins this: if they get over 80 degrees and do not continue up past 185 for 10 minutes to cure... then they'll never cure! I've seen pics of guys that didn't know a heat wave was coming in and left their stuff running out in the garage only to come back to a permanently gel-form of resin because it broke the 80 degree threshold but never went through the full cure cycle at >185. With that in mind I have to actually be very careful not to put even warm wood into the resin. This is why I have the giant ziplock bags to let the wood cool in (and not pick up moisture) after the drying or curing stages, before they go back into resin.

As for the info on how heat works in a thicker piece I'll have to read up more about this!

Best,

Chris

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I can't help but get the impression that this product is in fact somewhat crappy? Surely having predictable and reliable results should be the minimum? Is this literally the only product in this field or are there others?

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I wouldn't say that. Most guys using this are making MUCH smaller pieces... they buy toaster ovens that you attach a temp regulator to, etc. When you go big you start getting into much weirder territory. Sort of like the difference between baking a cupcake vs. a turkey. Turkey's gunna have a lot more considerations to get it right. You'll need bigger "tools" for the turkey too.

Also, most of the info out there is on the smaller stuff... but this has all been learn by doing (failing) for the guitar-sized pieces.

There are other companies with similar products, but the general rules apply to all of them.

Chris

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