Varnish Temperature


Recommended Posts

2 minutes ago, David Burgess said:

Those which "fill with gel" were probably never gas bubbles.

Particulates in a varnish film can't necessarily be seen, especially if they are roughly the same refractive index as the varnish. And a very tiny particle can result in a much bigger nit.

Like Mike mentioned, sheddings from paper towels can be a major offender. They can become completely transparent in a varnish with a similar refractive index to that of wood fiber. Even drying your hands with a newish cotton towel can contaminate your hands enough with lint to create a problem, if you are smearing the varnish with your hands. There's also the possibility of contaminating the varnish with skin dander. We're shedding it all the time.

These are just some things I've experienced myself, and may or may not be related to your issues.

I will be cognizant of this; any dirt that may be in the varnish may be there.  However, the  imperfections that I see are bubbles, as I see them scattered with a magnifying glass, and these bubbles make the surface rough, and this I what I am trying to eliminate.

Link to post
Share on other sites
  • Replies 114
  • Created
  • Last Reply

Top Posters In This Topic

I have had similar problems, I wonder if it’s air rising from the pores/gaps in the wood grain, or air trapped under the varnish, but this doesn’t explain the same on glass.

Mastic was not found in classical varnishes, but it can work nicely anyway, I don’t intend to bother anymore  as it is quite expensive. 

Link to post
Share on other sites
48 minutes ago, Anthony Panke said:

I have had similar problems, I wonder if it’s air rising from the pores/gaps in the wood grain, or air trapped under the varnish, but this doesn’t explain the same on glass.

 

Out-gassing from wood upon warming, as the entrained air expands, can certainly form varnish bubbles. I agree that this wouldn't be an explanation for what's happening with the varnish coating on glass.

Link to post
Share on other sites

I don't use solvents in my oil varnish, so I don't know if it makes a difference.  Anything that starts with "mineral" is a petroleum product.  Mineral turpentine is petroleum derived, whereas gum turpentine is derived from the distillation of tree sap.  For example, Diamond G makes their gum turpentine from slash pines.  Just something to think about.

Link to post
Share on other sites

I have tried washing the linseed oil (Barlean's food grade flax seed oil) and not washing it--it made no difference.  Now days, I use both Barlean's and the cold pressed oil from Kremer.   Both oils work for me.  I do not see how washing the oil would hurt anything; so, keep doing it if you wish.

The varnish problem appears to be dirt or some introduced dirt or particulate into the varnish.  Here are a couple of ideas:

1) Let the varnish settle--never shake it.  Pour the varnish off the top.

2) Filter the oil if there is still a problem--this will take out the particulates and the "worms'.

3) Use a fairly stiff brush to apply the varnish, and then  use the 'tip off' technique to level and break the fine bubbles.  Do a search if you do not know what 'tip off' means.  I never use a thumb to apply varnish--how will you get varnish into the corners?

Mike D

Link to post
Share on other sites
52 minutes ago, Jim Bress said:

I don't use solvents in my oil varnish, so I don't know if it makes a difference. 

I have experimented with a zillion different solvents and solvent combinations (well, maybe more like 60 :lol:), and have never had gas bubbles remaining in a dried varnish film on glass.

Link to post
Share on other sites
51 minutes ago, Janito said:

When you apply on glass, do the bubbles emerge at the edge of the brush fibres as you apply the varnish or does the bubbling happen later?

It happens while applying, not after; the more I brush it, the more bubbles instantly are created.

Link to post
Share on other sites
4 hours ago, Mike_Danielson said:

The varnish problem appears to be dirt or some introduced dirt or particulate into the varnish

The more I smear the varnish the more bubbles are created instantly; it seems to me that applying/agitating alone creates the bubbles in the varnish I make. 

Link to post
Share on other sites
26 minutes ago, Rimino said:

It happens while applying, not after; the more I brush it, the more bubbles instantly are created.

I think your problem is in the state of the brush when you dip into the varnish and your technique applying it to the surface.

You have air bubbles tapped by varnish/solvent between the hair fibres and these are being squeezed out as you brush.

(Reference: Personal communication)

Link to post
Share on other sites
  • 11 months later...
On 3/15/2019 at 5:31 PM, Rimino said:

I don’t know if I should trust the dial meat probe or the infrared and Bluetooth thermometers (both of which gave equal readings)

As my husband said...it depends on thermometers' accuracy...

For example:

Klein Tools IR10 has 20:1 distance (what is perfect) but has +-2% accuracy and may display inaccurate information.

Fluke 62 Max Plus has 12:1 distance but +-1% accuracy that is rare for the IR thermometers.

He used both and they displayed different temperature.

Found this article from the Fluke manufacturer - How to get great results with an infrared thermometer. I think this could be useful.

Link to post
Share on other sites
10 hours ago, Levietta said:

As my husband said...it depends on thermometers' accuracy...

For example:

Klein Tools IR10 has 20:1 distance (what is perfect) but has +-2% accuracy and may display inaccurate information.

Fluke 62 Max Plus has 12:1 distance but +-1% accuracy that is rare for the IR thermometers.

He used both and they displayed different temperature.

Found this article from the Fluke manufacturer - How to get great results with an infrared thermometer. I think this could be useful.

Thanks a lot, I’ll download and remember these steps mentioned in this article.  The infrared thermometer I bought is a Craftsman 10:1 dual laser infrared thermometer of my above three choices but on reading the article you referenced I have been forgetting to be extra careful so the laser doesn't reflect into my eyes off the metal pot or the varnish surface (which I read to be careful about in the Craftsman manual or somewhere on the web) although I don’t think it ever has.  I’ve made a few batches of varnish that work just fine, so I imagine the thermometer is mostly or sufficiently accurate.  Thanks a lot for your follow-up.

Link to post
Share on other sites

FWIW: the instrument, varnish and even brush must  be at the same room temperature.

The brush must be clean and dry. Flick the hair bristles in sunlight against a dark background to see if any dust flies off. Cleanliness is next to godliness. 

The varnish has rested for a day or more since agitation. Stirring is OK if bubbles are not created. In other words, do not use freshly made varnish.

Mulling and blending of pigment is also done well in advance.

Any solvent in the varnish has had a few days to outgas. I sometimes warm that varnish after mixing and put to the side to rest.

I thank @joerobson for much of this good advice provided over the years.

 

Link to post
Share on other sites

I don't have much to add, except that I apply my varnish warmed. It flows out better, there is less  possibility for runs, and because it's warmer, there is less surface tension to trap any bubbles created by brushing.

Link to post
Share on other sites
3 hours ago, Michael_Molnar said:

FWIW: the instrument, varnish and even brush must  be at the same room temperature.

The brush must be clean and dry. Flick the hair bristles in sunlight against a dark background to see if any dust flies off. Cleanliness is next to godliness. 

The varnish has rested for a day or more since agitation. Stirring is OK if bubbles are not created. In other words, do not use freshly made varnish.

Mulling and blending of pigment is also done well in advance.

Any solvent in the varnish has had a few days to outgas. I sometimes warm that varnish after mixing and put to the side to rest.

I thank @joerobson for much of this good advice provided over the years.

 

And let's add: do not use "brush soap" to clean up your brushes.  First clean with acetone. then rinse in turpentine,  then rinse in alcohol.   Let the brush dry and do the "flick it" test.

on we go,

Joe

Link to post
Share on other sites

Hey Joe!  Can you explain about the brush soap?  I've been cleaning my brushes (oil varnish) with brush soap and water for a while.  Doesn't do a great job. Reminder: I can't use turps. I just started using acetone after reading about it on on one of Mike's posts then followed up with soap and water as usual.  I was surprised by the emergence of a "worm track" where the varnish pulled away forming a short ribbon of no varnish.   Would acetone followed by alcohol work? How clean should each solvent wash be?

Thanks,

Jim

Link to post
Share on other sites
19 minutes ago, Jim Bress said:

Hey Joe!  Can you explain about the brush soap?  I've been cleaning my brushes (oil varnish) with brush soap and water for a while.  Doesn't do a great job. Reminder: I can't use turps. I just started using acetone after reading about it on on one of Mike's posts then followed up with soap and water as usual.  I was surprised by the emergence of a "worm track" where the varnish pulled away forming a short ribbon of no varnish.   Would acetone followed by alcohol work? How clean should each solvent wash be?

Thanks,

Jim

Hey Jim,

Brush soap is almost impossible to get completely out of the brush.  It hides up in the ferrule where it dries and becomes particles of various sizes.  When you use the "clean" brush these particles work there way down to the tip. When deposited on the surface,  varnish won't stick to them.   Tiny particles will show as bubbles.  Larger particles will cause fish eye.  Very large particles will cause those worm tracks you are seeing.

If you skip the turpentine wash, let the brush sit in alcohol overnight.   Then re-rinse in alcohol making sure it gets into the ferrule.

Can you use naphtha as a sub for turpentine?

To address the original question....it is nearly impossible to control cooking temperature in such a small batch.

on we go,

Joe

 

Link to post
Share on other sites
1 hour ago, joerobson said:

Hey Jim,

Brush soap is almost impossible to get completely out of the brush.  It hides up in the ferrule where it dries and becomes particles of various sizes.  When you use the "clean" brush these particles work there way down to the tip. When deposited on the surface,  varnish won't stick to them.   Tiny particles will show as bubbles.  Larger particles will cause fish eye.  Very large particles will cause those worm tracks you are seeing.

If you skip the turpentine wash, let the brush sit in alcohol overnight.   Then re-rinse in alcohol making sure it gets into the ferrule.

Can you use naphtha as a sub for turpentine?

To address the original question....it is nearly impossible to control cooking temperature in such a small batch.

on we go,

Joe

 

Thanks Joe.  You're a big help as always.  Fortunately just the single worm track.  Who wants a perfect straight varnish anyway. :) Naphtha will drop me as quick as turps and mineral spirits.  I think I'll just pick up fresh brushes for the final coat and never let them see anything besides acetone and EtOH.

-Jim

Link to post
Share on other sites
On 4/3/2020 at 9:38 AM, Michael_Molnar said:

Mulling and blending of pigment is also done well in advance.

 

On 4/3/2020 at 12:21 PM, Bill Yacey said:

I apply my varnish warmed

 

On 4/3/2020 at 12:48 PM, joerobson said:

do not use "brush soap"

Thanks, I looked at someone else’s varnish in the jar, applied it and it had bubbles also, extremely tiny when you look at it, so I realize my varnish itself might be fine.  I used my varnish again and therefore thought to apply in multiple layers and use steel wool on each layer as much as possible without taking the layer off and my varnish is starting to look better besides the fact I used artist’s Grumbacher turpentine and varnish makers linseed oil instead of Lowe’s turps and GNC flax oil that I washed although which didn’t alone solve the problem.  Once I learned the working method of how to make varnish it took me making a thorough mess and working with an impatient tireless questionable end in sight. I never knew it would be the same applying an already decent varnish which struck me with defeat after that. Does everyone else apply multiple coats of the color or a clear layer using steel wool and maybe pumice or sandpaper between each coat?

Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
  • Recently Browsing   0 members

    No registered users viewing this page.