I have had it explained to me that it is just like an avocado or an apple. It will turn brown over time. Since citric acid helps with an apple it also helps with woods like walnut and cherry to keep the white whiter. Even with lemon juice it will start to darken but the lemon juice will slow the progression and leave it whiter than with no treatment. HOW?? I slather the lemon juice all over the piece when I make my final cuts. Let it sink in and penetrate. As the wood dries out, some of the citric acid is left behind. After a few days I start the sanding sequence. After the last grit of sanding I slather on more lemon juice. I keep a bottle of "real Lemon" juice on my bench dedicated to this. Again after the last sanding and saturation with lemon juice you have to let it dry again. This will likely raise the grain so another light sanding with 400 or 600 grit will make it smooth again. I have tested this years ago, on two bowls from the same tree, with-and-without lemon juice, and the results are amazing. The bright white will fade but it will retain the contrast.It will darken somewhat with age, but I don't think it will ever convert into heartwood. The sapwood is effectively dead once it has lost a significant portion of its moisture. Most darkening is going to result from air oxidation, though there could be other factors involved as well.
I have had it explained to me that it is just like an avocado or an apple. It will turn brown over time. Since citric acid helps with an apple it also helps with woods like walnut and cherry to keep the white whiter. Even with lemon juice it will start to darken but the lemon juice will slow the progression and leave it whiter than with no treatment. HOW?? I slather the lemon juice all over the piece when I make my final cuts. Let it sink in and penetrate. As the wood dries out, some of the citric acid is left behind. After a few days I start the sanding sequence. After the last grit of sanding I slather on more lemon juice. I keep a bottle of "real Lemon" juice on my bench dedicated to this. Again after the last sanding and saturation with lemon juice you have to let it dry again. This will likely raise the grain so another light sanding with 400 or 600 grit will make it smooth again. I have tested this years ago, on two bowls from the same tree, with-and-without lemon juice, and the results are amazing. The bright white will fade but it will retain the contrast.
Indeed, citric acid (citrate) is a reducing agent that will inhibit air oxidation. This will certainly slow the process, though eventually the citrate itself will oxidize and won't be doing anything.I have had it explained to me that it is just like an avocado or an apple. It will turn brown over time. Since citric acid helps with an apple it also helps with woods like walnut and cherry to keep the white whiter. Even with lemon juice it will start to darken but the lemon juice will slow the progression and leave it whiter than with no treatment. HOW?? I slather the lemon juice all over the piece when I make my final cuts. Let it sink in and penetrate. As the wood dries out, some of the citric acid is left behind. After a few days I start the sanding sequence. After the last grit of sanding I slather on more lemon juice. I keep a bottle of "real Lemon" juice on my bench dedicated to this. Again after the last sanding and saturation with lemon juice you have to let it dry again. This will likely raise the grain so another light sanding with 400 or 600 grit will make it smooth again. I have tested this years ago, on two bowls from the same tree, with-and-without lemon juice, and the results are amazing. The bright white will fade but it will retain the contrast.
That is my experience also however my experience is limited to a couple of years.My experience has been that wet sap wood will dicolor but that once it's dry the color is pretty stable.