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Glue for beginners


aleron
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Hi All

I was wondering if some of the more experienced makers may like to contribute to a quick guide to their glue techniques... I know there are a million posts regarding glue on here and all are valuable sources of information, however I note some variance and conflicting approaches or are limited to one action. 

As a beginner I'm comfortable with woodworking and take my time to cut/carve with as much accuracy as I can, but when it comes to glue, I'm all thumbs!

To keep it simple, I thought I'd ask for your recipes for different parts so I can at least start on the right foot... 

I thought the below table might help me and other if you would be so kind to contribute 

Job   ------ Gram strength ------ Glue :water ratio (by weight) ------ Temp on application --------Note: 

e.g    

Blocks to form ------- 192g ---------- 1:2.75 ------------- 62degrees--------- medium thickness gels between fingers test 40sec

Ribs to sides

Glue sizing end grain

Joining belly & back centre 

Joining belly back to garland 

Setting neck 

I'm assuming all glueing will follow the basic principles of soak for a couple of hours and heat for a couple of hours no more than 62degrees to get ready for use. I've noticed a handful of very experienced makers suggesting temperatures up to 75degrees however glue guides suggest this is too high. Can you explain if this is the case or when this is fine? 

 

Thank you once again all. 

 

 

 

 

 

 

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17 hours ago, aleron said:

Hi All

I was wondering if some of the more experienced makers may like to contribute to a quick guide to their glue techniques... I know there are a million posts regarding glue on here and all are valuable sources of information, however I note some variance and conflicting approaches or are limited to one action. 

As a beginner I'm comfortable with woodworking and take my time to cut/carve with as much accuracy as I can, but when it comes to glue, I'm all thumbs!

To keep it simple, I thought I'd ask for your recipes for different parts so I can at least start on the right foot... 

I thought the below table might help me and other if you would be so kind to contribute 

Job   ------ Gram strength ------ Glue :water ratio (by weight) ------ Temp on application --------Note: 

e.g    

Blocks to form ------- 192g ---------- 1:2.75 ------------- 62degrees--------- medium thickness gels between fingers test 40sec

Ribs to sides

Glue sizing end grain

Joining belly & back centre 

Joining belly back to garland 

Setting neck 

I'm assuming all glueing will follow the basic principles of soak for a couple of hours and heat for a couple of hours no more than 62degrees to get ready for use. I've noticed a handful of very experienced makers suggesting temperatures up to 75degrees however glue guides suggest this is too high. Can you explain if this is the case or when this is fine?

I think it will be difficult to get many answers, because not many measure or have specific data on the glue they use. Also, always keep in mind that the dilutions and temperatures are variable depending on the type of glue you have and the gluing operations you need to do.

However, since I am one of those who indicate temperatures higher than 62 ° that are often indicated, I feel obliged to give some clarification.

I generally consider a temperature between 65° and 70° to be optimal, considering freshly prepared glue, not re-heated several times. Furthermore, after leaving the glue to soak in cold water for a few hours (mine requires at least three or four, it's a Japanese glue whose gram strength I don't know, but I estimate it around 300) I don't let it heat up for a couple hours, but I simply bring it to the temperature of use (it takes about twenty minutes to melt completely) and use it immediately, just to avoid prolonged overheating. If you plan to keep the glue at use temperature all day, perhaps it is better if it does not exceed 64/65 °(or 62° if you prefer).

The problem with the temperature is that the glue, once applied, begins to cool down, and if the temperature is already low it will almost immediately start to gel, especially if the pieces are not preheated, which is not good. A low temperature (62 °) is good if the gluing operation is very fast or if the environmental conditions are such as to delay the cooling. For this reason I prefer a higher temperature, to have more time margin, always with the premise that it is freshly prepared and used immediately without overheating it for a long time.

In the case of the central joints, where I indicate a temperature of maximum 75° (I usually stop heating at 72° if I don't get distracted:)), this is due to my gluing system, which involves transferring the glue into a small glass to pour it on the piece to be glued, and because I prefer not to heat the pieces of wood in order not to risk to deform them. All this will cause progressive cooling which will lower the temperature of the glue in the actual gluing, hence the higher temperature.

Regarding the dilution, I measure it only for the most critical gluings, and I established them by doing specific tests with my glue, for other glues they could be different:

Ribs to sides (do you mean ribs to blocks?): by eye, moderately thick

Glue sizing end grain : by eye, not much thick but not much thin, I continue to put it until it is no longer absorbed, so the dilution is not too decisive

Joining belly & back centre : 1:4 (thick)

Joining belly back to garland : by eye, not much thick but not much thin for the back, moderately thin for the top

Setting neck : 1:5 (fairly thick)

Bassbar : 1:5 (fairly thick)

Warning: do not follow my directions blindly, test your glue before using it for important gluing to get the right dilution ratio

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54 minutes ago, Davide Sora said:

I think it will be difficult to get many answers, because not many measure or have specific data on the glue they use. Also, always keep in mind that the dilutions and temperatures are variable depending on the type of glue you have and the gluing operations you need to do.

However, since I am one of those who indicate temperatures higher than 62 ° that are often indicated, I feel obliged to give some clarification.

I generally consider a temperature between 65° and 70° to be optimal, considering freshly prepared glue, not re-heated several times. Furthermore, after leaving the glue to soak in cold water for a few hours (mine requires at least three or four, it's a Japanese glue whose gram strength I don't know, but I estimate it around 300) I don't let it heat up for a couple hours, but I simply bring it to the temperature of use (it takes about twenty minutes to melt completely) and use it immediately, just to avoid prolonged overheating. If you plan to keep the glue at use temperature all day, perhaps it is better if it does not exceed 64/65 °(or 62° if you prefer).

The problem with the temperature is that the glue, once applied, begins to cool down, and if the temperature is already low it will almost immediately start to gel, especially if the pieces are not preheated, which is not good. A low temperature (62 °) is good if the gluing operation is very fast or if the environmental conditions are such as to delay the cooling. For this reason I prefer a higher temperature, to have more time margin, always with the premise that it is freshly prepared and used immediately without overheating it for a long time.

In the case of the central joints, where I indicate a temperature of maximum 75° (I usually stop heating at 72° if I don't get distracted:)), this is due to my gluing system, which involves transferring the glue into a small glass to pour it on the piece to be glued, and because I prefer not to heat the pieces of wood in order not to risk to deform them. All this will cause progressive cooling which will lower the temperature of the glue in the actual gluing, hence the higher temperature.

Regarding the dilution, I measure it only for the most critical gluings, and I established them by doing specific tests with my glue, for other glues they could be different:

Ribs to sides (do you mean ribs to blocks?): by eye, moderately thick

Glue sizing end grain : by eye, not much thick but not much thin, I continue to put it until it is no longer absorbed, so the dilution is not too decisive

Joining belly & back centre : 1:4 (thick)

Joining belly back to garland : by eye, not much thick but not much thin for the back, moderately thin for the top

Setting neck : 1:5 (fairly thick)

Bassbar : 1:5 (fairly thick)

Warning: do not follow my directions blindly, test your glue before using it for important gluing to get the right dilution ratio

Yup.  LIKE!!!! 

27 minutes ago, David Burgess said:

Great article.  Some may miss one of the most important hints David sticks in here, "Based on a 315g-strength glue......".  If, like me, you work in a semi-tropical heat-and-humidity area, using a strong glue weight is essential.  :)

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Suggestion, I'd recommend getting some glue { I also like 315 gram strength} with your pot and play around making various batches with scrap wood, with various types of glue ups, for example glue some edge to edge pieces mimicking gluing a center seam, then you could glue some "T"s as if a top were getting glued on a block, mess around with different water dilutions, for your applications, for example the top T you would want a glue that could be "fractured" or broken without taking a bunch of wood grain, whereas the seam joint you would want to see the wood break not the joint. All this to learn practical application. I feel practicing these things makes it so one has a better understanding of what they are really trying to do, that all joints are not going to be glued the same , for a reason, and to over all get comfortable , or more comfortable as a novice when its time to glue real work, it reduces apprehension.

The real challenge with hide glue, beyond what the David{e}s have imparted is SPEED WITHOUT SLOP, THE RIGHT AMOUNT, NOT TOO MUCH, AND NOT TOO LITTLE....that will be variable depending on the brush you use, so, practice so you will know how your brush will work, find a good brush and stick with it, it helps with consistency...If you ever watch high divers who are going to do some crazy 3 somersaults with a twist kinda thing you often see them doing a "dry run" in their head, waving their arms around before they jump, this is not a bad idea when doing a glue joint for beginners, get everything prepared first, have everything you want where you want it, practice {with a dry brush} picking up the material and putting it together and how you will initialize clamping if that is happening {ie. tops and backs to garlands} also if you plan on using heat in the form of a hair dryer or heat gun {for cold shop applications, general ease of making contact and time expansion} dry run that as well, make sure no cords can lasso anything LIKE THE GLUE POT to ensure a "routine" procedure with no problems.

One would think having two pieces of wood before you on a table and all you have to do is butter on some glue and slap them together with a little back and forth rub would be an easy procedure {and it is after doing it several times} but suddenly when you are a novice this seemingly easy thing can induce some panicky behavior that can lead to some messy stupid mistakes.

Also if you use wax paper, be careful not to pinch it in between the seams of plates, it is an easy novice mistake.

Also I suggest understanding what I call "The Hargrave method" for certain applications, that is to simply apply the glue, let it dry, put "it" where you want it, then brush on or with a syringe apply boiling hot water to reactivate the glue, best way to glue purfling IMO. Good luck , have fun, don't glue your eye shut.

Last word, try to find out what "glue ghosts" are and how to prevent them

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Thank you all for your input... I totally agree that practice with different ideas is the best however you're answers give me a good idea of where to start...

I did a back centre joint yesterday and heated up to about 72degrees are you have suggested David. It worked very well and I had more time to work with my rub joint and clamping. Much more successful than my belly joint which was applied when about 65degrees. I think I have been gelling too quickly as you suggest, which leads to construction panic and rushing!

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19 hours ago, Violadamore said:

Yup.  LIKE!!!! 

Great article.  Some may miss one of the most important hints David sticks in here, "Based on a 315g-strength glue......".  If, like me, you work in a semi-tropical heat-and-humidity area, using a strong glue weight is essential.  :)

Until fairly recently, I assumed that high gel strength = high bond strength, but the Christian Schabbon Strad article, which gave the "strongest glue award" to Amasonan 3B (gel strength ~ 140g) appeared to conclude otherwise. I don't pretend to understand the mechanisms for this*, but I have tried the Amasonan glue, and wasn't disappointed.

*I'd welcome an explanation.

 

Edited by Spelk
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2 hours ago, Spelk said:

Until fairly recently, I assumed that high gel strength = high bond strength, but the Christian Schabbon Strad article, which gave the "strongest glue award" to Amasonan 3B (gel strength ~ 140g) appeared to conclude otherwise. I don't pretend to understand the mechanisms for this*, but I have tried the Amasonan glue, and wasn't disappointed.

*I'd welcome an explanation.

 

In general, the higher the gram strength, the greater the water dilution required to give adequate working time, leaving less actual glue. So it can end up being kind of a wash, depending on the particular job you are doing.

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50 minutes ago, David Burgess said:

In general, the higher the gram strength, the greater the water dilution required to give adequate working time, leaving less actual glue. So it can end up being kind of a wash, depending on the particular job you are doing.

Yes, that makes sense, thanks. But I also remember seeing somewhere that while high gel strength glues give higher cohesive forces (ie the glue sticks to itself more strongly), adhesive forces between the glue and the wood are actually greater for lower gel strength glues. 

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Eventually you'll ditch any numbers and just doi it all by eye and feel. 

The only indicators that I use are how thin it dribbles off of my brush and how warm it feels between my fingers. 

But different strokes. 

I use a pretty medium glue mix for basically the whole violin. The only job that I use thinner blue for is gluing the top on. 

The key is setting up your clamps for optimal speedy gluing. 

I'll usually preheat center joints and neck sets. Sometimes fingerboards if I feel like it. 

I think what's also super important that is often overlooked is the amount of glue you lay down. Too much can really complicate things. 

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18 hours ago, Spelk said:

Until fairly recently, I assumed that high gel strength = high bond strength, but the Christian Schabbon Strad article, which gave the "strongest glue award" to Amasonan 3B (gel strength ~ 140g) appeared to conclude otherwise. I don't pretend to understand the mechanisms for this*, but I have tried the Amasonan glue, and wasn't disappointed.

*I'd welcome an explanation.

 

The higher the weight, the higher the melting point, for hide glue, and the better it resists heat and humidity.  :)

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60C seems to have been a trade off between workability and degradation- hide glue strength degrades over time with heating .2-1% per hour at 60c, quadruple that at 80C per a quote of a 1960s book. For industrial uses where you’d have a pot going all week this mattered. Somehow this percolated into wisdom as 60c is ideal.

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10 hours ago, Carl Johnson said:

60C seems to have been a trade off between workability and degradation- hide glue strength degrades over time with heating .2-1% per hour at 60c, quadruple that at 80C per a quote of a 1960s book. For industrial uses where you’d have a pot going all week this mattered. Somehow this percolated into wisdom as 60c is ideal.

Yep, that's the theory, but I have never been comfortable using glue only at 60 °, it gels too quickly, perhaps 62/63 ° is a little better, but maybe it's just my glue or my thermometer is not very accurate...:)

Weisshaar in his chapter on glue indicates 140/145 ° F (60/62 ° C) with an ambient temperature of 70/75 ° F (21/24 ° C). I keep my workshop at 19.5 ° C in the winter, so maybe that's why I need a higher glue temperature.

However, the key if using higher temperatures is to use heating times as short as possible, so as to avoid degradation.

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