Marcus Bretto

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About Marcus Bretto

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  1. 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 off? The long cook varnish I make has a very strong fire orange color just as it is, that darkens to shades of red in thicker layers, but I’ve been wanting to tone down the orange stage a bit and show a hint of bluish reds. I’m thinking about going with cochineal because if it’s natural tendency in that direction, but I’d love to be able to know how to adjust the color of the end product to the right side of the spectrum. Slightly more purples would probably get me exactly what I want. I’ve heard multiple people say making a cochineal lake is tricky. What is the tricky part about it? What is critical to pay attention to? I’ll also make up some test samples with Joe Robson’s alizarin varnishes mixed with mine. I can’t foresee any problems, as the oil/resin ratios are the same, but if anyone thinks this is a bad idea let me know. Any recommendations for other things to try would be great, as well. Thanks!
  2. 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 making, you’ll learn that you can adjust your times and temperatures depending on the state your resin and the state of your oil, whether it is bodied, raw, sun thickened, ect. With a highly cooked pine resin being combined with oil at 240 degrees Celsius, an hour is sufficient. If you find that you have a large percentage of precipitate upon cooling, and your varnish looks cloudy, Try to boost temperatures again. I would also reevaluate your oil to resin ratio. The most common varnishes hover at around 50:50 resin:oil by mass. A high resin(lean) oil varnish is good for use as a ground, where it is close to the wood, but they can be too hard and brittle for a main varnish. Heating oil and resin to these temperatures is dangerous. Be careful and think of your safety and health!
  3. 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.
  4. 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!
  5. 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.
  6. 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 bleached of its color (I should find the article again and post it) and I’m wondering if rosin that has been collected from turpentine distillation has, in effect, been stripped of some of its color carrying qualities from its long exposure in this sort of environment. I had heard that different resins respond quite differently in the process, but I’d also be curious to hear people’s experience with distillate byproduct resin vs oleoresins directly from the tree. Maybe partial confirmation of this can be realized.
  7. 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 lid to trap some heat and still let air in is better?
  8. 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?
  9. I’ve been bouncing ideas through my head about the color of aged/oxidized wood and started doing some investigation into wood byproducts when I came across Sodium Lignosulfonate. It’s a byproduct of removing lignin from wood in the paper pulping industry. It is a water soluble powder which can range in color from browns to reds to golds that also has properties as a dye dispersant. Something tells me it could be very good for adding some color to white wood. Any opinions? Thanks!
  10. @Don Noon I had the same thought, and was planning to put a secondary container inside of it to hold the varnish, probably with a layer of sand around it. Moving the whole thing around would definitely not be ideal!
  11. Hello all! So, I've been really excited about trying to cook my first batch of oil varnish. I've been researching the forums on here/ various things on the internet and getting supplies for the job. I was planning on purchasing a hotplate for cooking the varnish on when I discovered a "dip coat melting pot" while cleaning out the basement of our shop. It looks like an industrial glue pot with temperature control ranging from 100 to 500 degrees F. Looking them up online shows me that they are designed specifically for heating viscous materials evenly (plastics, resins, ect.) and often come with "thermostatic control to eliminate carbonization". Seems like its the sort of thing that would be perfect for cooking varnish! Has anyone done or heard of others using these things, or just have opinions on the matter? Also, any more varnish tips/ suggestions would be well appreciated. -Marcus
  12. Thank you for your response, Joe. I have had time to read portions of the Fry book since you're response. It certainly answers my question about drying times relating to oxidation, but I haven't seen any mention of his experimentation with other acids or oxidizers either in my reading or in a digital search of terms in the book. As far as I can see within my days of searching, there is no mention of anyone in the violin world branching out from using this acid, either. I have, however, found multiple scientific articles from the 1800 and 1900's demonstrating the use of other chemicals on resins and linseed oil, and a few of them seem promising in their results.
  13. Hello all. So I've been reading up on as much information as I can within reason about the use of nitric acid in the cooking of varnish to produce color. Of course, reading about it has made me aware of the potential problems in using varnish produced with nitric acid. Some people claim to have success and others have many complaints from color shifts to drying problems to cracking and all sorts of fun stuff. Putting all of this aside, I have three main questions, both highly related. Does anyone know what quality of nitric acid produces the production of the colorant? Is it the oxidizing quality or the strength of the acid itself? Could the unnatural oxidation be what interferes with the drying time? Also, has anyone tried to achieve similar results with the use of chemical products other than nitric acid?
  14. Hello all! This is Marcus Bretto of TB Smithy. I am now a full time luthier in Vermont, so my active work with TB smithy has been put on hold, however Mats Thureson (the owner) is a very talented smith, and while the site does not show it, Mats has been heading in the direction of becoming a full time bladesmith. Mats and I developed the treatment and the welding techniques for the steel in these knives a few years back, and it has since gone through rigorous testing by me in the field. They are still frequently sent to me for quality control before being sent out to the customer. We recognize that Etsy is certainly not the best platform for this sort of business, and this is something he is in the process of working on. Etsy will be replaced with a dedicated website in the future. In the mean time, feel free to contact either Mats or myself with any questions. Custom pieces can be made. Thank you! MarcusBretto: (781) 534-0394 or at Mats Thureson: (781) 534-1305 Or at