Michael_Molnar

A natural drier is umber because it contains Mn. Check out the driers sold by Woodfinishing Enterprise. I now use Siccatif de Courtrai made by James C. Groves. It contains Pb and Mn which will turn off some makers. However, it is powerful. Just a few drops does it.

Yes, @Geigenbauer, this is indeed a lot of fun. I love the test plates. You are on the right track.

Thanks, Dennis. Very useful thread.

My issue with templates is that they don’t tell me how to blend the surfaces between the templates. Therein lies the rub.

@John Masters gave me a bunch of Condax’s violin wood. I found it useless.

Please do some reading of old MN threads on this subject.

Doing decent antiquing is difficult. I won’t even try it after seeing so many disasters at VSA shows. It is a major skill set as Burgess mentioned.

I stand corrected. Thank you.

Good suggestion that’s worth a shot.

I had 2 or 3 break a few years ago and stopped using them

I’ll hazard a guess that you are seeing the solvent dominating the fluorescence at the start. As it evaporates or dissipates the roasted rosin is left to fluoresce. I’d need to do some simple tests to evaluate that hypothesis.

Not enough information. Give details about the varnish.

Thank you, Captain Obvious.

I forgot that Sherlock Holmes was a research source. Yes, there are a number of papers that come up with googling. They explain how aged linseed oil eventually fluoresces. Old dried linseed oil glows and looks opaque under UV. Recently, I was rereading B&G and noted that Greiner p.29 said that the fluorescence takes a few years to develop fully. Varnish, however, glows on day 1 and remains strong for centuries. Do not confuse linseed oil with varnish. The fluorescence of varnish, new or old, is mostly due to rosin (colophony).

My favorite planet.

Use Burgundy Rosin in lieu of Juniper gum.

Very nice photos.

Ask Burgess. He knows lots about spray guns. I experimented with them eons ago. You will need good ventilation to carry away the unused spray before it settles on everything in the room. I still drag out my TeleVue refractor for quick views. It’s a lot f fun.

Consider using a spray gun for spirit varnish on a large instrument.

Fresh oil doesn’t fluoresce. The aging process develops fluorescence. So, it must not be simply a process of retaining certain bonds, but developing others that either fluoresce or no longer prohibit fluorescence.

Dried linseed oil will fluoresce after it yellows over time. Will this explain the fluorescence observed from the under coat beneath the colored varnish layer? I know that a lean clear varnish fluoresces very brightly. Will a thin linseed oil film do this too? Any research into this?

Parchment paper has a coating of silicone. It works.

Let me add this. Stradivari did vary his varnish system over time. The biggest change was around 1696 when he moved from an Amati system to his own that appears on his Golden Period instruments. I believe that there is evidence for another change after ~1730. Moreover, there are subtle variations even during the Gold Period. My own experiments show that methods of making varnish/ground and their application to wood also produce variations. This is why I advocate having one Stradivari violin available for testing by all the major researchers. That would reduce the noise.

Nice review, Michael. I agree with your interpretation of B&W’s “rubble”. My jury is still out with Echard”s linseed oil interpretation. As far as B&G goes, I suggest focusing on Brandmair’s section.

The determination of the rosin:oil ratio is on p. 140 f.19 of B&G. My reading says the cooking was done at 120C which seems low to most varnish makers. However, for FTIR analysis this cooking temperature won't change results - so I am told. Anyhow the 4:1 ratio works for me. It wears the right way (easily) and looks right under UV.