todd goldenberg Posted October 22, 2019 Report Share Posted October 22, 2019 We seem to be mixing rosin just cooked and varnish. So my question is what is the role of the oil as it continues to polimerize. What other things are being added to the cooking process, you know your secrets. What is the source of the rosin, what degree of processing has it had.My experience is oil left to age will tend to yellow in color. This over time to my eye effects the varnish more than the rosin. Which I think is very stable. Quote Link to comment Share on other sites More sharing options...
joerobson Posted October 22, 2019 Report Share Posted October 22, 2019 7 hours ago, todd goldenberg said: We seem to be mixing rosin just cooked and varnish. So my question is what is the role of the oil as it continues to polimerize. What other things are being added to the cooking process, you know your secrets. What is the source of the rosin, what degree of processing has it had.My experience is oil left to age will tend to yellow in color. This over time to my eye effects the varnish more than the rosin. Which I think is very stable. True that the linseed oil on its own will yellow over time if left in the light. I don't know how see this effect in a finished varnish. Yes. The source and color of the rosin to begin with is of primary importance! on we go, Joe Quote Link to comment Share on other sites More sharing options...
Guest Posted October 22, 2019 Report Share Posted October 22, 2019 13 minutes ago, joerobson said: True that the linseed oil on its own will yellow over time if left in the light. I don't know how see this effect in a finished varnish. My experience agrees with Tad Spurgeon's paper on linseed oil. When using the hot water, salt and sand method to refine the raw oil, over time the oil will lighten and will get very clear if left on a window sill in the sunlight. Perhaps it's the mucilage and junk in the raw oil that yellows over time. Once washed out my oil has gotten very clear but takes time on a window sill in UV. Read the paper here..........https://www.tadspurgeon.com/content.php?page=just+oil Quote Link to comment Share on other sites More sharing options...
joerobson Posted October 22, 2019 Report Share Posted October 22, 2019 5 minutes ago, Ernest Martel said: My experience agrees with Tad Spurgeon's paper on linseed oil. When using the hot water, salt and sand method to refine the raw oil, over time the oil will lighten and will get very clear if left on a window sill in the sunlight. Perhaps it's the mucilage and junk in the raw oil that yellows over time. Once washed out my oil has gotten very clear but takes time on a window sill in UV. Read the paper here..........https://www.tadspurgeon.com/content.php?page=just+oil True. Well washed oil will behave as you state. The yellowing is part of the effect of the curing film. Joe Quote Link to comment Share on other sites More sharing options...
Michael_Molnar Posted October 22, 2019 Author Report Share Posted October 22, 2019 On 10/22/2019 at 1:59 AM, David Burgess said: For testing light-fastness, here's what I suggest: Apply your varnish equally to two glass slides. Use the thickness and color intensity that you would expect to use on a violin (UV has very low penetration of most varnishes). Also, use the finished product as it is when mixed with oil, because behavior of the resin Oh, one more-more thing: Cook and darken a resin too long, and it will no longer melt into and truly combine with hot vegetable oil. Instead, it will be incorporated as more of a pigment suspension (or some parts of it will), which will change the optical qualities, maybe for better or worse, depending on your perspective. I have seen this too. I nicknamed it "the blob". Linseed oil will not mix (crosslink?) with it unless I whip them as in a blender. I believe that there is a threshold for cooking that crosses from oxidation to carbonization. It depends on temperature and time. If the temperature approaches 300 C I see carbonized pieces in the mix. I now get better results with a mechanical stirrer that I discussed elsewhere. It reduces the likelihood of hot spots and skin/film surfaces that inhibit oxidation. Quote Link to comment Share on other sites More sharing options...
Michael_Molnar Posted October 22, 2019 Author Report Share Posted October 22, 2019 I want to add this important point that many varnish makers forget: In my experience to date, a good cooked rosin varnish still needs colorants (pigments or dyes). If your wood ground is strongly colored, you could get away with just cooked rosin varnish. Now, having said that, I think there may be a way to get a permanent cooked rosin varnish that is red, not just brown/black. No one has shown me one yet. Again, I'm talking about a brushable varnish, not solid rosin. Here's another observation: I wonder whether a yellowed linseed oil is such a bad thing in a cooked rosin varnish. I'll have more to say about this in the future. For the last week, I have been in Tasmania and today in Melbourne. I'll be back at the bench in 2 weeks. Stay tuned. Quote Link to comment Share on other sites More sharing options...
Don Noon Posted October 23, 2019 Report Share Posted October 23, 2019 Just out of curiosity... What happens if you cook linseed oil alone for a very long time? I know it gets thick, but will it eventually cook down to some kind of colored resin that can be made into a varnish by cooking again with linseed oil? Quote Link to comment Share on other sites More sharing options...
Michael_Molnar Posted October 23, 2019 Author Report Share Posted October 23, 2019 2 hours ago, Don Noon said: Just out of curiosity... What happens if you cook linseed oil alone for a very long time? I know it gets thick, but will it eventually cook down to some kind of colored resin that can be made into a varnish by cooking again with linseed oil? If you cook it too long you get linoleum, or something like it. A short cook in a vacuum is closer to boiled linseed oil. I guess you want something that will still crosslink with rosin for a true varnish. @joerobson would know, I'm sure. Quote Link to comment Share on other sites More sharing options...
joerobson Posted October 23, 2019 Report Share Posted October 23, 2019 12 hours ago, Michael_Molnar said: If you cook it too long you get linoleum, or something like it. A short cook in a vacuum is closer to boiled linseed oil. I guess you want something that will still crosslink with rosin for a true varnish. @joerobson would know, I'm sure. Long cooking linseed oil under controlled temperatures yields a stiff jelly like stuff called "sweet meats" which was used to polish tap dance shoes. Linoleum is cooked linseed oil + rosin + sawdust. Linseed oil cooked in a vacuum...Stand Oil...is not suitable for varnish making. Colophony and varnish a few more days under the lights. Quote Link to comment Share on other sites More sharing options...
Michael_Molnar Posted October 23, 2019 Author Report Share Posted October 23, 2019 1 hour ago, joerobson said: Colophony and varnish a few more days under the lights. How about taking better photos? What about BLO for varnish making? Quote Link to comment Share on other sites More sharing options...
joerobson Posted October 23, 2019 Report Share Posted October 23, 2019 2 minutes ago, Michael_Molnar said: How about taking better photos? What about BLO for varnish making? Photos...I guess I need a new phone... Commercial boiled linseed oil is just raw linseed oil with an indeterminate amount of cobalt drier added. Problems there.... on we go, Joe Quote Link to comment Share on other sites More sharing options...
Guest Posted October 23, 2019 Report Share Posted October 23, 2019 19 hours ago, Don Noon said: Just out of curiosity... What happens if you cook linseed oil alone for a very long time? I know it gets thick, but will it eventually cook down to some kind of colored resin that can be made into a varnish by cooking again with linseed oil? Quote Link to comment Share on other sites More sharing options...
Guest Posted October 23, 2019 Report Share Posted October 23, 2019 21 hours ago, joerobson said: Long cooking linseed oil under controlled temperatures yields a stiff jelly like stuff called "sweet meats" which was used to polish tap dance shoes. Linoleum is cooked linseed oil + rosin + sawdust. Linseed oil cooked in a vacuum...Stand Oil...is not suitable for varnish making. Once the oil reaches "sweet meats" will it still dry on it's own? ...and can it still be crosslinked and made into a varnish?,...or should you discard it? How long does it take linseed to reach that stage? Quote Link to comment Share on other sites More sharing options...
Guest Posted October 23, 2019 Report Share Posted October 23, 2019 Please check the Luthiers Exchange for the varnish books (which dispels fiction from fact) still available for sale. Quote Link to comment Share on other sites More sharing options...
Jim Bress Posted October 23, 2019 Report Share Posted October 23, 2019 I’m not completely sure what this thread is really about. Whether it’s trying to prove, disprove, or explore “Roger Hargrave’s” varnish as he described in the Making a Bass blog. For reference, I just finished a cook about the same time this thread started. I think this batch is a good representation of the varnish I think we’re talking about. Joe Thrift taught me how to make it, so it’s Roger’s varnish two cooks removed. The rib stock started “white” and sealed with clear (platina) shellac. Over the last 10 days I applied 4 finger pat layers as thin as I could apply evenly, the same as if I was varnishing a fiddle. The last layer was applied 4 days ago. That’s approximately 240 hrs. In the UV box. The thickness of the varnish is thinner than my ability to measure. Just trying to give context to the conversation, whatever the conversation is actually about. Quote Link to comment Share on other sites More sharing options...
scordatura Posted October 23, 2019 Report Share Posted October 23, 2019 18 minutes ago, Ernest Martel said: Please check the Luthiers Exchange for the varnish books (which dispels fact from fiction) still available for sale. Just looked at your listings. It says 2 of your varnish book listings are sold. Quote Link to comment Share on other sites More sharing options...
Guest Posted October 23, 2019 Report Share Posted October 23, 2019 3 minutes ago, scordatura said: Just looked at your listings. It says 2 of your varnish book listings are sold. Sorry the varnish books I'm talking about are these.... Quote Link to comment Share on other sites More sharing options...
Guest Posted October 23, 2019 Report Share Posted October 23, 2019 13 minutes ago, Jim Bress said: I’m not completely sure what this thread is really about. Whether it’s trying to prove, disprove, or explore “Roger Hargrave’s” varnish as he described in the Making a Bass blog. For reference, I just finished a cook about the same time this thread started. I think this batch is a good representation of the varnish I think we’re talking about. Joe Thrift taught me how to make it, so it’s Roger’s varnish two cooks removed. The rib stock started “white” and sealed with clear (platina) shellac. Over the last 10 days I applied 4 finger pat layers as thin as I could apply evenly, the same as if I was varnishing a fiddle. The last layer was applied 4 days ago. That’s approximately 240 hrs. In the UV box. The thickness of the varnish is thinner than my ability to measure. Just trying to give context to the conversation, whatever the conversation is actually about. Are you happy with that result? Quote Link to comment Share on other sites More sharing options...
Jim Bress Posted October 23, 2019 Report Share Posted October 23, 2019 7 minutes ago, Ernest Martel said: Are you happy with that result? Yes I am. However, My post was to give an example for the discussion. I’m happy to subject my sample or additional samples to explore how this varnish will perform under different conditions. Quote Link to comment Share on other sites More sharing options...
Guest Posted October 23, 2019 Report Share Posted October 23, 2019 8 minutes ago, Jim Bress said: Yes I am. However, My post was to give an example for the discussion. I’m happy to subject my sample or additional samples to explore how this varnish will perform under different conditions. How your varnish will perform? What does that mean? If this is the method you learned from the workshop and you are are happy with the results why ask how it will perform under different conditions? What conditions? Did you not ask that in the workshop? Quote Link to comment Share on other sites More sharing options...
Jim Bress Posted October 24, 2019 Report Share Posted October 24, 2019 3 minutes ago, Ernest Martel said: How your varnish will perform? What does that mean? If this is the method you learned from the workshop and you are are happy with the results why ask how it will perform under different conditions? What conditions? Did you not ask that in the workshop? E, I’m not asking any questions. This thread appears to be talking about Rogers varnish without anyone making the varnish. It’s the varnish I make, so I’m offering it up as an example to provide context to the conversation. If I’m off base, then my contribution will be ignored, and that’s fine. Quote Link to comment Share on other sites More sharing options...
Guest Posted October 24, 2019 Report Share Posted October 24, 2019 16 hours ago, Jim Bress said: E, I’m not asking any questions. This thread appears to be talking about Rogers varnish without anyone making the varnish. It’s the varnish I make, so I’m offering it up as an example to provide context to the conversation. If I’m off base, then my contribution will be ignored, and that’s fine. The OP question is whether cooked rosin is fugitive. I agree once posters start dropping big names threads can get misguided. Bottom line is I think MM raises a good point and one that I agree with. Quote Link to comment Share on other sites More sharing options...
Guest Posted October 24, 2019 Report Share Posted October 24, 2019 @scordatura The books are still available. One interested person changed their mind. I updated the thread. Quote Link to comment Share on other sites More sharing options...
Marty Kasprzyk Posted October 24, 2019 Report Share Posted October 24, 2019 Somebody will eventually find the fugitive rosin. Quote Link to comment Share on other sites More sharing options...
DonLeister Posted October 24, 2019 Report Share Posted October 24, 2019 On 10/21/2019 at 8:26 AM, Jim Bress said: I think the important variable is the % colophony reduction by weight. You will need to reduce the colophony by ~80%. Basically getting your cooked rosin as dark as possible without burning. Jim, what is the ratio of oil to resin? And is that all the varnish ingredients? Quote Link to comment Share on other sites More sharing options...
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