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After laying down my first coats of Holtier varnish, it became obvious that one or two nights in the UV light box isn't going to cut it. I've heard repeated claims that it requires a drier. I'm assuming purchasing the Holtier Catalyst is the common sense route to go, even if a small bottle plus shipping is a bit pricey for what it is, but the cost isn't a big deal. I'm assuming one separates a small quantity of varnish from the bottle and a a drop or two of catalyst is added? The instructions don't mention a method of adding it.

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I do not know exactly what Eugene is using for a drier.  One might assume a cobalt based Japan.

If so do not exceed 4% by volume.   Excess drier will over-catalyse the varnish and make it crumbly.

on we go,

Joe

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Thin coats of Holiter varnish applied with your fingers or a pad should dry overnight in a drying cabinet. Heck i could get his stuff to dry to the touch with a few hrs of strong sunlight. 

if you do use a cobalt or japan dryer and you varnish with your finders or palm, make sure to wear gloves. 

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Perhaps my light cabinet is on the weak side. I just have basic flourescent black light bulbs, which worked fine for turpene varnish, but this is taking longer. I'll give it to the weekend before I decide to use a drier with the next coats. I did test strips a few months back, I don't recall exactly how long it took but I don't recall it being particularly sluggish.

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5 minutes ago, Woodland said:

Perhaps my light cabinet is on the weak side. I just have basic flourescent black light bulbs, which worked fine for turpene varnish, but this is taking longer. I'll give it to the weekend before I decide to use a drier with the next coats.

How many bulbs, of what size, in what volume of space, with what sort of reflective coating on the interior?

I would heed Joe's warning about incorporating catalysts (or too much catalyst) into the varnish mix. At what point to they stop working, becoming benign?

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It's a home made (aren't they all?) box I inherited from a local luthier's estate. It's 18 x 24 x 36, lined with aluminum foil. It has four 24", 20W fluorescent black light bulbs, plus two CFL black light bulbs mounted close to the floor of the box. I also installed a rotisserie motor to rotate the instrument. The bulbs I'm guessing are less than ideal for varnish curing, but they did work for Fulton's turpene varnish just fine. I just got home and gave the violin a check, and it does appear to be coming along, as some spots seem fairly dry. I think it's also important to remember that it's just the first coat, which is likely to take the longest amount of time to dry. For the record I didn't use any of the Holtier ground "system", rather a dewaxed blonde shellac as a sealer/ground.

This being a home made box wired by someone I never even met does arouse some safety concerns. I was going to wait until I start making cellos to set up a grow tent with all new lighting, but maybe now might be a better time. I think if I'm patient enough the current bulbs will eventually do their job. 

Any suggestions for bulb upgrades, perhaps Reptile UVB bulbs?

 

IMG_6282.JPG

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4 hours ago, David Burgess said:

How many bulbs, of what size, in what volume of space, with what sort of reflective coating on the interior?

I would heed Joe's warning about incorporating catalysts (or too much catalyst) into the varnish mix. At what point to they stop working, becoming benign?

Never.  A peroxide catalyst (actually an initiator) would exhaust, and most UV cures are inhibited peroxides.

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9 hours ago, Woodland said:

That looks like the variety of bulb that was included with the box when I acquired it. I wasn't able to find them when I needed replacements, so I went with the current black light bulbs.

In my experience, the cylindrical BLB (Black Light Blue) bulbs you have can work fine. They just have a coating which filters out more of the visible light, compared to the bulbs Jim has. (I have no experience with the compact fluorescent blacklight bulbs)

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Nearly every oil varnish I've encountered will present drying challenges if applied too thickly - the surface, being exposed to the air, will more readily oxidize/polymerize than the air starved portion of the coat nearest the wood. You may consider trying a different application technique before resorting to driers, which are quite toxic and can create their own problems. Thinning and brushing, padding off until the coat is very thin and even, etc. 

Making or buying varnish is just the start - no matter what you use, you have to play with it until you understand how it wants to be treated.

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25 minutes ago, JacksonMaberry said:

Making or buying varnish is just the start - no matter what you use, you have to play with it until you understand how it wants to be treated.

I totally agree with that. It is like having a good instrument, you still have to know how to play it.

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  • 2 weeks later...

Update: The first coat took the better part of a week to dry in the UV lightbox, but for the first coat that's pretty normal. No chemical dryer necessary. My generic black light bulbs are adequate. Did the second coat last night and it's drying more quickly. Currently working on getting the lightbox temperature down into the 70's, as it's a bit warm in there. I have one computer fan working with another on the way, current temp is in the 80's.

That Holtier varnish is interesting stuff. It's almost like applying a glaze rather than a varnish. Getting the color to even out takes practice to keep it from getting blotchy, but there is some diffusion of the color as it settles in the warm lightbox before it starts to cure. I'm getting something of an "antiquey" look, which is fine. It develops an orange peel texture as it's curing. I'm also shading the varnish as I go through the progressive coats. We'll see how it goes.

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14 minutes ago, Woodland said:

Update: The first coat took the better part of a week to dry in the UV lightbox, but for the first coat that's pretty normal. No chemical dryer necessary. My generic black light bulbs are adequate. Did the second coat last night and it's drying more quickly. Currently working on getting the lightbox temperature down into the 70's, as it's a bit warm in there. I have one computer fan working with another on the way, current temp is in the 80's.

That Holtier varnish is interesting stuff. It's almost like applying a glaze rather than a varnish. Getting the color to even out takes practice to keep it from getting blotchy, but there is some diffusion of the color as it settles in the warm lightbox before it starts to cure. I'm getting something of an "antiquey" look, which is fine. It develops an orange peel texture as it's curing. I'm also shading the varnish as I go through the progressive coats. We'll see how it goes.

None of this sounds good.

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1 hour ago, Woodland said:

Currently working on getting the lightbox temperature down into the 70's, as it's a bit warm in there. I have one computer fan working with another on the way, current temp is in the 80's.

The ballasts from the tube light fittings produce a lot of heat, it’s best to wire the lights so that the ballasts are outside of the box. 

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10 hours ago, Woodland said:

 Currently working on getting the lightbox temperature down into the 70's, as it's a bit warm in there. I have one computer fan working with another on the way, current temp is in the 80's.

A temperature in the 80's should be fine (and a higher temperature will react the varnish faster) IF you can keep the humidity from going too low.

Indoor humidity at 70 degrees in the Great Lakes area is already dangerously low right now (I'll estimate 10-20% relative humidity) unless you are adding large amounts of supplemental moisture. Raising the temperature of that indoor air by another 15 degrees in your drying box will make it even drier.

Always monitor the relative humidity in your drying cabinet using an accurate hygrometer.

During this cold spell, I'm evaporating several gallons of water per day to keep my shop up to 40% relative humidity. Heating that 40% air another 15 degrees in a drying box would drop the humidity in the box to ~25%.

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I have an accurate digital hygrometer that I keep in the shop. I keep a 12 x 12 glass baking dish full of water in the box to help with humidity. Even so, the relative humidity at 82 degrees is in the 20th percentile, not good enough. Perhaps if I install the second fan to flow across the water dish that will help things.

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39 minutes ago, Woodland said:

I have an accurate digital hygrometer that I keep in the shop. I keep a 12 x 12 glass baking dish full of water in the box to help with humidity. Even so, the relative humidity at 82 degrees is in the 20th percentile, not good enough. Perhaps if I install the second fan to flow across the water dish that will help things.

Better still, put a small atomizer in the pan of water and connect it to a hygrometer - I do this and my lightbox is always between 40 and 45 % RH. I've posted photos in an old lightbox thread, try searching "grow tent".

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5 hours ago, Woodland said:

I have an accurate digital hygrometer that I keep in the shop. I keep a 12 x 12 glass baking dish full of water in the box to help with humidity. Even so, the relative humidity at 82 degrees is in the 20th percentile, not good enough.

A 12 x 12  inch evaporative surface area won't be enough to do much. Instead, moisten a terrycloth towel, and hang it over a towel rack with the lower ends immersed in water. This will increase the evaporative surface area maybe 100 to 1000 times.

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https://www.amazon.com/AGPTEK-Aluminum-Fountain-Fishtank-Birdbath/dp/B00PAK245E/ref=asc_df_B00PAK245E/?tag=hyprod-20&linkCode=df0&hvadid=193980915053&hvpos=&hvnetw=g&hvrand=2837153357314398592&hvpone=&hvptwo=&hvqmt=&hvdev=m&hvdvcmdl=&hvlocint=&hvlocphy=9033829&hvtargid=pla-313799861009&psc=1

Put one of these in the pan of water. Use an online duct fan to vent air out the top of the cab. Have a filtered intake at the bottom of the cab - this way convection is working with your ventilation. Connect the atomizer to Burgess's favorite humidistat. Move the ballast outside the cab if it's not there already. You now have zero heat and humidity issues and full control over both. Enjoy!

 

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