Measuring Hide Glue Temperature

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Measuring Hide Glue Temperature

Postby Steve Gonwa » Mon Dec 18, 2017 2:55 am

My question is about measuring the temperature of hot hide glue. I am new to this and I'm using the Hold Heet glue pot.

Assume that I place properly mixed glue into a small glass or plastic jar and place the jar inside the pot. Water is added to the pot to about the level of the glue in the jar. Many sources suggest the optimal temperature to heat the glue up to is 145 degrees F.

But is that measured by the water temperature or the actual GLUE temperature ? What I have found is that the glue takes longer to heat up to 145 degrees than the water does. When the water inside the pot reaches a temperature of about 145 degrees, the glue temp is actually lower than that, only about 130 degrees. But the glue consistency looked OK to use. When the water temp rose to about 155-165 degrees, then the glue itself actually rose to 145 ( my pot seems to heat higher than the optimal 140-150 the Hold Heet people say it heats up to ).

It looks like many people just wait for the water temp to get to 145 and then go ahead with the gluing as long as the consistency looks OK. Is that fine to do, or does the GLUE itself need to reach 145 degrees to be at the proper temperature for use ? I would like to get away with using just one thermometer.

Should I leave the thermometer in the water, heat the water to 145 and not worry that the glue itself might be at a lower temp than 145, or measure the temp in the glue itself ?

Thanks
Steve
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Re: Measuring Hide Glue Temperature

Postby Mark Fogleman » Mon Dec 18, 2017 5:58 am

The "optimal" temp allows swings of 10 - 15 degrees to happen with duty cycle swings of the heater. Like your kitchen oven, you are only at the set temp twice per duty cycle...on the way up while the power is on to the element and on the way down when the power is off. It is not as precise as your thermometer. Using 135 degree glue works fine and doesn't change the adhesive quality of the glue. If you feel you need to give yourself some insurance with temperature it will only shorten the working time slightly at 135. With any glue and glue batch you need to glue a few joints the get the feel of the glue's properties. I have found that getting temp in the ballpark and learning how much working time I have for HHG open time for that specific glue is the focus, not specific temps. This relationship changes slightly from batch to batch. Even if you go over a little you can still use the glue. You just shouldn't go over consistently which over time will breakdown the glue.

When it comes to glue questions I always ask myself...what would Stradivarius have done?
We are too worried about such small incremental minutia which can get in the way of the primary goal.
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Re: Measuring Hide Glue Temperature

Postby Mario Proulx » Mon Dec 18, 2017 1:10 pm

The glue pot won't cycle, since it is a fixed wattage. Leave the glue in long enough for it to reach the same temp as the water. Covering the glue container speeds the process a lot.

If in a hurry, you can added some boiling water to the pot, but keep an eye on the glue temp. If you shoot much over 145, you begin to break down the protein chains that make it work...
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Re: Measuring Hide Glue Temperature

Postby Christ Kacoyannakis » Mon Dec 18, 2017 1:43 pm

What I did to speed the process is to do a few test runs of heating up water in the microwave. So I know I need 2 cups of water in my copper pot. I figured out how many minutes and seconds to heat 2 cops of cold water in the microwave to bring it to 145. Then I just heat up the water the same way every time, and then you don't have to wait for the water to come up to temperature. I usually refrigerate my glue between work sessions, so I put it in the water bath when I get into the shop, and it warms up pretty quickly, because I don't make a lot of glue at a time. I used to make big batches and the pour it into ice cube trays and freeze the cubes, but that isn't really necessary. I just make a small batch every couple of work days.
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Re: Measuring Hide Glue Temperature

Postby Mark Fogleman » Mon Dec 18, 2017 2:33 pm

Mario Proulx wrote:The glue pot won't cycle, since it is a fixed wattage.

It has a thermostat. I'm no Tesla but to me this says it is sending power to a heating element in a cyclic fashion. You can buy a replacement Hold Heet thermostat here:https://www.infinish.com/index.php/e202661.html
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Re: Measuring Hide Glue Temperature

Postby Steve Gonwa » Tue Dec 19, 2017 2:15 am

Thanks much for the replies and information.

Today I decided to do some adjustments on the Hold Heet pot thermostat. You have to open the unit up, but it's very simple to do. After a number of very slight trial and error adjustments, I was able to get the following readings on the water and actual glue temperatures:

30 minutes
Water temp 149.9
Glue temp 139.5

60 minutes
Water temp 150.9
Glue temp 142.5

90 minutes
Water temp 150
Glue temp 144.7

120 minutes
Water temp 150.8
Glue temp 142.4

I also used a smaller baby food jar this time rather than the small mason jar I used previously. It has thinner walls and less glass to heat up and maintain at temperature.

Does this look good to go ? I don't think I could get this any closer to a glue temp of 145 by messing with the thermostat further ( I don't think Mr. Stradivarius could either ! ) It's at the high end of the Hold Heet spec'd range of 140-150, but that would seem fine.

Does the heating time seem appropriate to you experienced hide glue users ? It seems like it takes a good 45-60 minutes to get the glue temp close to equilibrium with the water temp, at least within a few degrees. Is that typical for hide glue ?

I know I'm overthinking this, but preventing problems sometimes makes the learning curve a bit easier. Thanks again for any input.

Steve
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Re: Measuring Hide Glue Temperature

Postby Mark Fogleman » Tue Dec 19, 2017 5:49 am

Looks like you are good to go! Very tight spec on the heated water bath which you should expect for a Hold Heet. Only better option would be the Sous Vide device we use in the kitchen which has a circulating pump.
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Re: Measuring Hide Glue Temperature

Postby Matthew Lau » Tue Dec 19, 2017 6:39 pm

I'll add another thing:

Sometimes, you'll see "dental hot water baths" on ebay.
These are excellent and very precise.
They were used for hydrocolloid impressions--a super accurate, very technique sensitive material for crown and bridge that is no longer being sold. The material had to be heated within a few degrees of accuracy to be effective.
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Re: Measuring Hide Glue Temperature

Postby Clay Schaeffer » Tue Dec 19, 2017 8:26 pm

"very technique sensitive material for crown and bridge that is no longer being sold"

I take it there were too many failures.......
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Re: Measuring Hide Glue Temperature

Postby Jim McConkey » Tue Dec 19, 2017 10:37 pm

Since you are using baby food jars, I want to add a warning. If you refrigerate the leftovers, let the water cool before taking the jar out to put in the fridge, and allow the jar to warm to room temperature before putting into the hot water bath. If you take the jar directly out of the fridge and put it in hot water, your jar might shatter. DAMHIK
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Re: Measuring Hide Glue Temperature

Postby Steve Gonwa » Wed Dec 20, 2017 2:37 am

Thank you for that safety warning. I wouldn't have thought that was necessary but good to know.
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Re: Measuring Hide Glue Temperature

Postby Clay Schaeffer » Wed Dec 20, 2017 12:40 pm

I have been using small squeeze bottles with long tapered tips for HHG. I think my wife found them at Michael's or JoAnn fabrics. Less prone to temperature shock and makes dispensing easy.
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Re: Measuring Hide Glue Temperature

Postby Bryan Bear » Wed Dec 20, 2017 2:24 pm

Also, if you are using glass jars, don't forget to but the jar away and let the glue dry in the jar. It will shrink as it dries but not let go of the glass bottom. The glue will pull big chips out of the bottom of the jar. I was dong some strength tests with re-hydrated glue, it took me a while to figure out why I kept finding glass chips in my samples.
PMoMC

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Re: Measuring Hide Glue Temperature

Postby Mario Proulx » Wed Dec 20, 2017 3:18 pm

Plastic squeeze bottles, with a handful of stainless steel bolts added to keep the bottle from floating around, are the best way to go. Hair color bottles are perfect. If you don't know a lady who colors her hair, go to any hair salon and ask. They'll have plenty of empties...
Mine is 18+ years old and still going fine...
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