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Marcus Bretto

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  1. Ah, that is interesting to read! I learned a bit more about why nitrates and nitrites are the ph, that they are, and I find it interesting that very few people mention using Sodium and Potassium nitrATE, even though they are neutral in solution. Also, I believe in Helen Michetschlager’s analysis of Koen Padding’s primers, there were many nitrATES, including ammonium nitrate, which would seemingly break down forming ammonia gas as a byproduct. That sounds better than leaving alkali salts behind in the wood.... I’ve noticed that oxidizers tend to tan more red in UVA, and more green in UVB a
  2. @Jim Bress hi Jim! I think there must be a misunderstanding, I did not use a ph indicator strip. I dyed the wood Itself, with a ph reactive dye. And I have tested the dye with UV alone, and it is extremely lightfast. But yes, I suppose something else may be causing it to change color
  3. Hi all! I did an experiment yesterday by putting a pH indicating dye on a strip of maple. I let that dry, and then applied 5% sodium nitrite solution to it, and placed it in the light box. To my surprise, only after a few minutes of light exposure the dye changed from orange to a cool red, indicating the presence of a base. I had always thought that nitrite reaction produces nitric acid, so, I’m very confused as to why this test indicates as alkaline. Anyone have a possible explanation? Also, I’m wondering if this is a good approach to create a pH neutral treatment? I’m not a chemist, but I im
  4. I was under the impression that a rosinate and an abietate are two words for the same type of compound, for the same reasons@Michael Szyper describes. Abietic acid is the main and most reactive component in rosin, no? also, aren’t most (If not all) rosinate/rosin soaps somewhat water reactive? @Salve Håkedal I understand this concern, and I’m hoping further pyrolysis reactions would solve the problem. But it seems many makers have success with rosinate in varnish, so I don’t think I’ll write it off just yet haha.
  5. If I find anything else worth noting in my experiments, I'll be sure to post it here.
  6. Thanks so much for sharing the info, all! I still haven't had the chance to do anything with it, but we'll see what happens with some more free time.
  7. Has anyone here ever had experience using an Ammonium Rosinate in oil varnish? I just made up a very small amount, and it seems to have some nice properties! I just want to consult the masses before I make a big mistake in using it for something. Here are some (bad) photos of a thin layer rubbed into fresh, bare rib wood, unsealed. It's a much more lively, rich color in person. Transparency and depth is also not well shown here. I prepared a 70/30 solution of grain alcohol and laboratory grade ammonia (30% Concentration), and to that, I added enough crushed rosin to make a thin spiri
  8. Hello all! Starting to get into lake pigments! So, to jump right in: when you’re making a lake pigment, what part of the process does pH have an impact on color? I’ve heard of people using acidic, neutral, and alkaline extractions for the dyestuff, but I’m curious as to how/if the ph of the extraction plays into the final pigment color. My thoughts are that it is really the pH of the final suspension that makes the biggest impact, but I just don’t know. Could you take dry, finished pigment and expose it to a medium of different pH to change the color? Will it keep this color upon drying o
  9. From what I’ve experienced, your temperatures are not high enough for the majority of your resinous constituents to bond with the oil. Abietic acid based resins have varying temperatures in which they will start to incorporate into the oil depending on how they are processed: it seems the higher the melting point of the resin, the higher the temperatures necessary to properly bind it with the oil. For resin that is not highly cooked, I’d suggest a temperature of 200 degrees CELCIUS held for a minimum of 3 hours. Less time, and you’re likely to have drying problems. As you get into varnish maki
  10. Thanks for sharing! Part of me doubts they are still doing this in more advanced manufacturing facilities. Plenty of companies are using CNC to machine plates and carve scrolls these days.
  11. Does anybody have pictures or ideas of how the better violin manufacturing companies are producing their rib structures and setting necks? I’m curious about what type of forms they may be using, how the ribs and linings are getting bent, how they’re leveling things off, jigs for routing neck mortises, ect. Anything that’s quick, efficient, and works!
  12. I wanted to start this topic with the hopes that it would become a useful resource for those who are looking to go in a particular direction with wood and ground coloration and are unsure of a place to start. Of particular interest to me is producing a wood color that leans on tan with grey hints. Not much yellow, and very little green. But, it would be nice to see everything that’s out there. If you have examples of any process you’d like to share, even if you didn’t like the result, it would be wonderful to have here in one place.
  13. Thank you guys for the response. I am coming to the realization that the Kremer dark colophony is probably not a good product as far as cooking color into the resin. Over the long time of cooking, some of the brown/green hue was mitigated by a gold/red shift, and I say some, purposefully. But I am worried that, without the use of excessive heat and some carbonization, which I understand should be avoided, this resin simply won’t take on enough color to be used on its own. A few days ago I came across an article demonstrating how rosin cooked in an oxygen free environment can actually be bleach
  14. Hello all. So, I’ve started cooking down some dark colophony from Kremer to get color for varnish. The internal temperature of the melt is reading right at 200C but the surface that is exposed to air keeps cooling/hardening over and I’m afraid it is making the cook take considerably longer to darken. It’s been on for over 100 hours with not much color change and very little volume reduction. Is this something that I am right to worry about, and if so, any suggestions as for how to combat it? Would adding turpentine and cooking at a lower (safer) temperature be an option? Or perhaps a vented li
  15. Thanks, both of you, for your input! @joerobson how did you find the color and other qualities? Was it simply not nice enough to bother finding a solution to the unevenness?
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