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8 hours ago, Nick Allen said:

Oi, Jim, what kind of chalk are you using for bass bars? I find that regular gypsum chalk tends to compact into the wood of the top, and then the chalk won't lay down onto the top wood any longer. 

I think you want to avoid “dustless” chalk. I won’t be much help. I found the chalk I use in an antique store. It works great. I just looked at the company’s website and what they offer now is different. 

-Jim 

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2 hours ago, Jim Bress said:

I just looked at the company’s website and what they offer now is different. 

-Jim 

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...every.....TIME!!! lol. 

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1 hour ago, Nick Allen said:

...every.....TIME!!! lol. 

https://www.amazon.com/Mercurius-Blackboard-Chalk-White-pcs/dp/B01E09QRYO/ref=sr_1_3?keywords=mercurius+chalk&qid=1570202809&sr=8-3

Not to intrude; but this is the nearest analogue to the old Pelikan chalk in both form and formula. Soft enough to lay on top of the wood without packing down the fibres like the more common, excessively-hard gypsum chalks; but densely pigmented enough to actually stay visible long enough to be useful.

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37 minutes ago, LethbridgeViolins said:

https://www.amazon.com/Mercurius-Blackboard-Chalk-White-pcs/dp/B01E09QRYO/ref=sr_1_3?keywords=mercurius+chalk&qid=1570202809&sr=8-3

Not to intrude; but this is the nearest analogue to the old Pelikan chalk in both form and formula. Soft enough to lay on top of the wood without packing down the fibres like the more common, excessively-hard gypsum chalks; but densely pigmented enough to actually stay visible long enough to be useful.

Ooh! Thanks! 

I like your bass bar jig, Jim, btw. 

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1 hour ago, LethbridgeViolins said:

https://www.amazon.com/Mercurius-Blackboard-Chalk-White-pcs/dp/B01E09QRYO/ref=sr_1_3?keywords=mercurius+chalk&qid=1570202809&sr=8-3

Not to intrude; but this is the nearest analogue to the old Pelikan chalk in both form and formula. Soft enough to lay on top of the wood without packing down the fibres like the more common, excessively-hard gypsum chalks; but densely pigmented enough to actually stay visible long enough to be useful.

Hey, get off my lawn! :D  Just kidding.  Nice tip.

26 minutes ago, Nick Allen said:

Ooh! Thanks! 

I like your bass bar jig, Jim, btw. 

This is the relatively cheap (compared to aluminum)  "Grandi Livtai" bass bar frame that IVC sells.  Stiff, thin, and light.  A big improvement over the plywood frame I was using.  

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The varnish I've been using on the last couple of instruments is based on Roger Hargrave's recipe.  Worked well, black in a jar, and still dark in a blob of any thickness greater than a varnish layer.  I wasn't satisfied with how dark the varnish would get with 3 thin applications without adding more color during application.  Three thin layers is as thick as I want to go.  I had a 100 ml left of the previous cook so I decided to try to darken it up.  I added 50 g of FF rosin cooked down 90% by weight (because that's when the rosin told me to stop).  I melted the rosin with 45 g of linseed oil at 200 C then added it to my existing varnish once it cooled down to 100 C and added a bit of mastic tears to keep the resin ratios consistent.

I prepared the rib cut off by burnishing with shave grass then sealing it with clear shellac rubbed on. I applied a single thin before and after varnish layer using finger pats to apply the varnish just as I would do during actual application.  The rib was partially bent so it took two pics to capture the before and after shots.  The right side has my original varnish and the left has the additional color from cooked rosin added.  The pic was taken after 5 hours in UV that made the sample dry to the touch.  Fortunately this worked well. :) Otherwise I would be cooking a whole new batch of varnish.  

Cheers,

Jim

Cooked rosin chip still red if viewed from a thin enough cross section

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Cook set-up

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Varnish sample on white porcelain

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Befor (right) and after (left) on sealed ribstock

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On 10/13/2019 at 10:39 AM, Jim Bress said:

A riddle...what happens when the inner lid of your jar of linseed oil is stuck. 

You get a well oiled bench. <_<

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A Gentleman in every respect (now deceased) Sam Compton, relayed a story to me of some linseed oil he had stored in a glass jar that was placed on a shelf in a closet.

One day it just exploded, or rather imploded from the oil sucking the O2 out of the jar, glass shards were driven into the Sheetrock wall, like a small grenade explosion. Needless to say picking up one of those when they are at their limits could be uncomfortable to say the least. A hole in the lid with a piece of tape over it to provide vacuum relief or just use a plastic container would work. I have some old linseed in plastic that is sucked down unbelievably far.

Proceed with caution,,,,

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42 minutes ago, Evan Smith said:

A Gentleman in every respect (now deceased) Sam Compton, relayed a story to me of some linseed oil he had stored in a glass jar that was placed on a shelf in a closet.

One day it just exploded, or rather imploded from the oil sucking the O2 out of the jar, glass shards were driven into the Sheetrock wall, like a small grenade explosion. Needless to say picking up one of those when they are at their limits could be uncomfortable to say the least. A hole in the lid with a piece of tape over it to provide vacuum relief or just use a plastic container would work. I have some old linseed in plastic that is sucked down unbelievably far.

Proceed with caution,,,,

Huh, that scenario never occured to me.  Having made plenty of my own mistakes, I'm always happy to learn from other people's mistakes.  Thanks for the cautionary tale.

-Jim

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4 hours ago, Evan Smith said:

A Gentleman in every respect (now deceased) Sam Compton, relayed a story to me of some linseed oil he had stored in a glass jar that was placed on a shelf in a closet.

One day it just exploded, or rather imploded from the oil sucking the O2 out of the jar, glass shards were driven into the Sheetrock wall, like a small grenade explosion. Needless to say picking up one of those when they are at their limits could be uncomfortable to say the least. A hole in the lid with a piece of tape over it to provide vacuum relief or just use a plastic container would work. I have some old linseed in plastic that is sucked down unbelievably far.

Proceed with caution,,,,

Pinhole with tape... I wonder if the same described implosion could happen to a fat oil varnish left unchecked for years? I keep oil in glass but keep cracking the lids as preventative maintenance.

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Yu can fill the bottle with propane to replace air (oxygen) before closing. The oil or varnish will hold longer with no crust or skin.

You can use ordinary long-nose gas lighter (blow the fire off and keep the gas going). The gas is heavier than air so if you close lid slowly you will have minimum of oxygen inside. Or you can throw glass balls inside to lift the  oil level up to the lid and minimize oxygen.

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1 hour ago, HoGo said:

Yu can fill the bottle with propane to replace air (oxygen) before closing. The oil or varnish will hold longer with no crust or skin.

You can use ordinary long-nose gas lighter (blow the fire off and keep the gas going). The gas is heavier than air so if you close lid slowly you will have minimum of oxygen inside. Or you can throw glass balls inside to lift the  oil level up to the lid and minimize oxygen.

If you open up the picture of my linseed oil jar to magnify it you'l see that it is full of marbles.  Some folks use bloxygen and other use a drop of acetone then light it. putting the cap on traps the CO2 as the O2 is used up.  I haven't bothered with any of those yet.  It is coming time for my LO to migrate to a smaller jar.

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24 minutes ago, Jim Bress said:

If you open up the picture of my linseed oil jar to magnify it you'l see that it is full of marbles.

Yup, now I see them!

Now, that reminds me I've got half empty bottle of LO stored for almost 20 years somewhere in my varnish cabinet. I'd better check it :-)

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One questionable anecdote isn't going to make me worry too much about imploding canning jars, which are intended for vacuum anyway.  I don't seem to remember huge concerns about incandescent bulbs (much thinner) or TV picture tubes (much bigger).  However, it does seem a good idea to use an oxygen-free cover gas for varnish (even though I haven't been doing that).

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On 11/12/2019 at 7:53 AM, Don Noon said:

One questionable anecdote isn't going to make me worry too much about imploding canning jars, which are intended for vacuum anyway.  I don't seem to remember huge concerns about incandescent bulbs (much thinner) or TV picture tubes (much bigger).  However, it does seem a good idea to use an oxygen-free cover gas for varnish (even though I haven't been doing that).

If it came from Sam Compton it's is not questionable, It wouldn't be a problem if everything was made perfectly, but a flawed jar could possibly implode and take your eyes out, my jars are stored at eye level,

I am cautious,, I need to move slow and think twice,,,, and as you could probably guess, Don,,, I have been known to do some impulsively stupid things before.

Just a word of warning,,,,,

rumor has it that you should never make any stupid fast moves around Jim,,,

He'll take you out like a Ninja on Steroids!

Right Jim!

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No not our conversations Jim, but "Our" conversations "about" Jim!

"We" were just gossiping about you behind your back,

about when "We" had sampled too much "Spirit Varnish Thinner" and happened upon "Jim" in a sudden and uncontrolled manner,

When suddenly "Jim's" Training" kicked in and "we" found ourselves on the floor laughing, and "We" are still laughing about it!

Sometimes it's good to hang around someone that has their "Shit Together"

My 10 year old son still talks about hanging with "Mr Scientist" and your conversations with him,,,,,,,,,,,,,,,,, He's a sharp kid huh?

That's what I like the most about workshops and conventions and the like, it's the people,

It's the good 'ol days!

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