Re: 8660C restoration attempt
If the problem is in one of the PLLs (and it sounds like it may be), the diagnostic module is VERY helpful.
If you have it, you will probably have more hair after you finish the 8660 that if you try without the diagnostic module.
Cheers!
Bruce
Quoting RubenRubio <rubenrb2019@...>:
toggle quoted message
Show quoted text
Hello again
Some updates -
Hz and SWP keys are now fixed. Not so easy, have to file the stud after glue to ensure proper slide.
Seven power supply filter caps are now substituted with no significant improvement on ripple. Great news ??
The freq drift still there. I¡¯ve observed that the drift isn¡¯t only 5.9 MHz, but also 3 or 9 or 12 MHz, always multiple of three. ?Different drift values happens when restart the unit. It gives me the feeling that it jumps from loop to loop and that those loops are 3 megahertz.?I also think that on one occasion, with a low frequency, the output was ok, but I'm not sure, I have to try more times. The horrid skirt below 100 Hz of RBW is still there with any freq input. I¡¯ll try to mess more time with it to extract more reliable info about this.
Tried sweep function, it clicks and moves but sometimes the whole signal disapears or only few harmonics are present.
86634A phase modulator doesn¡¯t produce any variation in the wave, so maybe it¡¯s faulty too.
I¡¯ll buy the artek manuals to keep pulling the string¡
Regards,
Ruben
|
Re: 3335A - extender cards
No - lets talk about extender cards
Cheers!
Brce
Quoting Radu Bogdan Dicher <vondicher@...>:
toggle quoted message
Show quoted text
..."low standard"...
as opposed to "high standard' as I'm sure everyone figured out
On Thu, Sep 22, 2022 at 7:22 PM Bruce <bruce@...> wrote:
Lets talk off line
Cheers!
Bruce
Quoting Radu Bogdan Dicher <vondicher@...>:
Thank you, Dave.
Assuming it's the same guy I'm thinking of ("sparko6079" as eBay handle) I
have a bit of experience with that person, enough to not want to touch his
business with a ten foot pole.
I almost never do this, as I'm rabidly in favor of sustaining small (and
hopefully local) business, and have an unreasonably high standard for
unacceptable situations when it comes to those (having owned several, and
well aware of how difficult that is, particularly as far as customer needs
catering goes)... That guy has been off the charts with me.
So, again, assuming it's the same guy we're talking about, I really
appreciate the lead, but no, thank you.
Radu.
On Thu, Sep 22, 2022 at 6:44 PM Dave McGuire <mcguire@...> wrote:
On 9/22/22 21:30, Paul Amaranth wrote:
Extender cards are so basic you could actually fab one with a piece
of copperclad and a dremel with a cutoff disk (and a steady hand
or a good ruler). Mark and cut carefully and you can get something
usable. Really doesn't matter if you cut into the substrate as long
as you don't go through. There's a guy up in the New England area who makes extender cards on
a mill for various HP and other instruments and sells them on eBay.
LSSM had him make a custom extender card for a Varian 620 computer last
year. It needed some copper whisker cleanup, but it works. I've
forgotten his name, but he shouldn't be difficult to find.
-Dave
--
Dave McGuire, AK4HZ
New Kensington, PA
|
Re: 3335A - extender cards
Well, that sucks, I'm sorry to hear it. That's the same guy, yes. I've purchased a few extenders from him, and as I mentioned, one of our guys at LSSM (who is also here) had that custom extender done by him last year. No issues thus far, but I'll watch my back.
-Dave
toggle quoted message
Show quoted text
On 9/22/22 22:20, Radu Bogdan Dicher wrote: Thank you, Dave.
Assuming it's the same guy I'm thinking of ("sparko6079" as eBay handle) I have a bit of experience with that person, enough to not want to touch his business with a ten foot pole.
I almost never do this, as I'm rabidly in favor of sustaining small (and hopefully local) business, and have an unreasonably high standard for unacceptable situations when it?comes to those (having owned several, and well aware of how difficult that is, particularly as far as customer needs catering goes)... That guy has been off the charts with me.
So, again, assuming it's the same guy we're talking about, I really appreciate the lead, but no, thank you.
Radu.
On Thu, Sep 22, 2022 at 6:44 PM Dave McGuire <mcguire@... <mailto:mcguire@...>> wrote:
On 9/22/22 21:30, Paul Amaranth wrote:
> Extender cards are so basic you could actually fab one with a piece
> of copperclad and a dremel with a cutoff disk (and a steady hand
> or a good ruler).? Mark and cut carefully and you can get something
> usable.? Really doesn't matter if you cut into the substrate as long
> as you don't go through.
? ?There's a guy up in the New England area who makes extender
cards on
a mill for various HP and other instruments and sells them on eBay.
LSSM had him make a custom extender card for a Varian 620 computer last
year.? It needed some copper whisker cleanup, but it works.? I've
forgotten his name, but he shouldn't be difficult to find.
? ? ? ? ? ? ? -Dave
--
Dave McGuire, AK4HZ
New Kensington, PA
--
Dave McGuire, AK4HZ
New Kensington, PA
|
Re: 3335A - extender cards
..."low standard"...? as opposed to "high standard' as I'm sure everyone figured out
On Thu, Sep 22, 2022 at 7:22 PM Bruce < bruce@...> wrote: Lets talk off line
Cheers!
Bruce
Quoting Radu Bogdan Dicher <vondicher@...>:
> Thank you, Dave.
>
> Assuming it's the same guy I'm thinking of ("sparko6079" as eBay handle) I
> have a bit of experience with that person, enough to not want to touch his
> business with a ten foot pole.
>
> I almost never do this, as I'm rabidly in favor of sustaining small (and
> hopefully local) business, and have an unreasonably high standard for
> unacceptable situations when it comes to those (having owned several, and
> well aware of how difficult that is, particularly as far as customer needs
> catering goes)... That guy has been off the charts with me.
>
> So, again, assuming it's the same guy we're talking about, I really
> appreciate the lead, but no, thank you.
> Radu.
>
> On Thu, Sep 22, 2022 at 6:44 PM Dave McGuire <mcguire@...> wrote:
>
>> On 9/22/22 21:30, Paul Amaranth wrote:
>> > Extender cards are so basic you could actually fab one with a piece
>> > of copperclad and a dremel with a cutoff disk (and a steady hand
>> > or a good ruler).? Mark and cut carefully and you can get something
>> > usable.? Really doesn't matter if you cut into the substrate as long
>> > as you don't go through.
>>
>>? ? There's a guy up in the New England area who makes extender cards on
>> a mill for various HP and other instruments and sells them on eBay.
>> LSSM had him make a custom extender card for a Varian 620 computer last
>> year.? It needed some copper whisker cleanup, but it works.? I've
>> forgotten his name, but he shouldn't be difficult to find.
>>
>>? ? ? ? ? ? ? ?-Dave
>>
>> --
>> Dave McGuire, AK4HZ
>> New Kensington, PA
>>
>>
>>
>>
>>
>>
>
>
>
|
Re: 3335A - extender cards
Lets talk off line
Cheers!
Bruce
Quoting Radu Bogdan Dicher <vondicher@...>:
toggle quoted message
Show quoted text
Thank you, Dave.
Assuming it's the same guy I'm thinking of ("sparko6079" as eBay handle) I
have a bit of experience with that person, enough to not want to touch his
business with a ten foot pole.
I almost never do this, as I'm rabidly in favor of sustaining small (and
hopefully local) business, and have an unreasonably high standard for
unacceptable situations when it comes to those (having owned several, and
well aware of how difficult that is, particularly as far as customer needs
catering goes)... That guy has been off the charts with me.
So, again, assuming it's the same guy we're talking about, I really
appreciate the lead, but no, thank you.
Radu.
On Thu, Sep 22, 2022 at 6:44 PM Dave McGuire <mcguire@...> wrote:
On 9/22/22 21:30, Paul Amaranth wrote:
Extender cards are so basic you could actually fab one with a piece
of copperclad and a dremel with a cutoff disk (and a steady hand
or a good ruler). Mark and cut carefully and you can get something
usable. Really doesn't matter if you cut into the substrate as long
as you don't go through. There's a guy up in the New England area who makes extender cards on
a mill for various HP and other instruments and sells them on eBay.
LSSM had him make a custom extender card for a Varian 620 computer last
year. It needed some copper whisker cleanup, but it works. I've
forgotten his name, but he shouldn't be difficult to find.
-Dave
--
Dave McGuire, AK4HZ
New Kensington, PA
|
Re: 3335A - extender cards
Thank you, Dave.?
Assuming it's the same guy I'm thinking of ("sparko6079" as eBay handle) I have a bit of experience with that person, enough to not want to touch his business with a ten foot pole.?
I almost never do this, as I'm rabidly in favor of sustaining small (and hopefully local) business, and have an unreasonably high standard for unacceptable situations when it?comes to those (having owned several, and well aware of how difficult that is, particularly as far as customer needs catering goes)... That guy has been off the charts with me.?
So, again, assuming it's the same guy we're talking about, I really appreciate the lead, but no, thank you.? Radu.?
On Thu, Sep 22, 2022 at 6:44 PM Dave McGuire < mcguire@...> wrote: On 9/22/22 21:30, Paul Amaranth wrote:
> Extender cards are so basic you could actually fab one with a piece
> of copperclad and a dremel with a cutoff disk (and a steady hand
> or a good ruler).? Mark and cut carefully and you can get something
> usable.? Really doesn't matter if you cut into the substrate as long
> as you don't go through.
? ?There's a guy up in the New England area who makes extender cards on
a mill for various HP and other instruments and sells them on eBay.
LSSM had him make a custom extender card for a Varian 620 computer last
year.? It needed some copper whisker cleanup, but it works.? I've
forgotten his name, but he shouldn't be difficult to find.
? ? ? ? ? ? ? -Dave
--
Dave McGuire, AK4HZ
New Kensington, PA
|
Re: 3335A - extender cards
JCLPCB seems to be less expensive for 4 inch by 6 inch boards (cheap size/special is 4 inches by four inches).? This is for HASL dual sided boards, roughly 5 of each, adding gold fingers, beveled edges and the like will be more.? SeeedStudio is more expensive once you get out of the 4x4 range.
No experience with others.
Harvey
toggle quoted message
Show quoted text
On 9/22/2022 9:30 PM, Paul Amaranth wrote: Extender cards are so basic you could actually fab one with a piece
of copperclad and a dremel with a cutoff disk (and a steady hand
or a good ruler). Mark and cut carefully and you can get something
usable. Really doesn't matter if you cut into the substrate as long
as you don't go through.
You can use the vinegar/salt/hydrogen peroxide to etch them at home
if you can use some kind of resist (toner transfer, UV film, sharpie,
paint, etc).
Just file a slight bevel on the fingers for easier insertion.
Lots of free CAD systems for PCBs out there including web based if you
want to send it out to a board house for something more professional
looking (and things like gold plating on the fingers). The only
problem is extender cards tend to be larger than the cutoff size for
really cheap boards. Still cheaper than finding an OEM card or
having an engineering firm make one up for you.
I had a script for gEDA to generate edge connector footprints.
Should probably dig that out; I need an extender card for an 8754A.
Paul
On Thu, Sep 22, 2022 at 05:49:50PM -0700, Radu Bogdan Dicher wrote:
Douglas Electronics doesn't have ready-to-go 3335A cards. Not sure I can go
custom on these cards for this one project. I have no pricing on that yet
(still talking to them), but I can't imagine that path is feasible for a
hobbyist project.
If anyone has files to share to create a PCB for this, that would be
fantastic.
Thank you,
Radu.
|
Re: 3335A - extender cards
On 9/22/22 21:30, Paul Amaranth wrote: Extender cards are so basic you could actually fab one with a piece
of copperclad and a dremel with a cutoff disk (and a steady hand
or a good ruler). Mark and cut carefully and you can get something
usable. Really doesn't matter if you cut into the substrate as long
as you don't go through. There's a guy up in the New England area who makes extender cards on a mill for various HP and other instruments and sells them on eBay. LSSM had him make a custom extender card for a Varian 620 computer last year. It needed some copper whisker cleanup, but it works. I've forgotten his name, but he shouldn't be difficult to find. -Dave -- Dave McGuire, AK4HZ New Kensington, PA
|
Re: 3335A - extender cards
Extender cards are so basic you could actually fab one with a piece
of copperclad and a dremel with a cutoff disk (and a steady hand
or a good ruler). Mark and cut carefully and you can get something
usable. Really doesn't matter if you cut into the substrate as long
as you don't go through.
You can use the vinegar/salt/hydrogen peroxide to etch them at home
if you can use some kind of resist (toner transfer, UV film, sharpie,
paint, etc).
Just file a slight bevel on the fingers for easier insertion.
Lots of free CAD systems for PCBs out there including web based if you
want to send it out to a board house for something more professional
looking (and things like gold plating on the fingers). The only
problem is extender cards tend to be larger than the cutoff size for
really cheap boards. Still cheaper than finding an OEM card or
having an engineering firm make one up for you.
I had a script for gEDA to generate edge connector footprints.
Should probably dig that out; I need an extender card for an 8754A.
Paul
toggle quoted message
Show quoted text
On Thu, Sep 22, 2022 at 05:49:50PM -0700, Radu Bogdan Dicher wrote: Douglas Electronics doesn't have ready-to-go 3335A cards. Not sure I can go
custom on these cards for this one project. I have no pricing on that yet
(still talking to them), but I can't imagine that path is feasible for a
hobbyist project.
If anyone has files to share to create a PCB for this, that would be
fantastic.
Thank you,
Radu.
--
Paul Amaranth, GCIH | Manchester MI, USA
Aurora Group of Michigan, LLC | Security, Systems & Software
paul@... | Unix/Linux - We don't do windows
|
Re: 3335A - extender cards
Douglas Electronics doesn't have ready-to-go 3335A cards. Not sure I can go custom on these cards for this one project. I have no pricing on that yet (still talking to them), but I can't imagine that path is feasible for a hobbyist project.?
If anyone has files to share to create a PCB for this, that would be fantastic.? Radu.?
You could see if Douglas Electronics are still going in CA.
They offered a large stock of extenders for common pitches/widths.? I bought a bunch and used some as-is, others I modified or cut down to suit particular instruments.? Gave me a very useful result.
|
A quick update on this project, though no breakthrough yet.
At this point, with hands-on help from members here (= Ozan!) I am still investigating?multiple paths of possible failure, but an increasingly?likely culprit is the?VCO (Bruce - very likely right on the money!).?
Still hopeful I can either acquire or fabricate some riser cards to continue this troubleshooting, but so far no distinct progress.?
I don't think I can progress without?those, so if you have any tucked aside that require the first born, I am willing to discuss! :)
Thank you all for helping with this. Radu.?
On Sun, Sep 18, 2022 at 9:01 PM Bruce < bruce@...> wrote: Radu -
Entirely possible, but I have (surprisingly) seen few serious problems?
cluse by power supply failure in HP instruments.? Some but not many.
I would still take a look at the no DELTA_F problem first.? Kinda?
speaks to a VCO problem or at least a VCO not changing frequency due?
to some control problem.? Next best guess is a mixer malfunction (but?
I think this is less likely).
I would try to find out where the ~ 21 MHz signal is coming from and?
then see what controls that source.? A likely culpert is a "stuck" VCO?
- and the problem becomes WHY is it stuck.? A problematic VCO PLL /?
PLL detector seams a likely candidate.
Keep on having fun :-)
Cheers!
Bruce
Quoting Radu Bogdan Dicher <vondicher@...>:
> Bruce,
> I think there are two independent issues (still) going on at the same time.
> So my initial gut feeling there may be one single trouble point triggering
> this eclectic set of fails we're looking at currently was probably overly
> optimistic. At least as far as I can tell right now.
> I wonder if the power supply event took a bunch of things offline with it.
> It's the only way I can figure what seems to be two outstanding issues left
> on the docket after fixing one.
> Radu.
>
> On Sun, Sep 18, 2022 at 7:24 PM Bruce <bruce@...> wrote:
>
>> I was going to point that out.
>>
>> If it was the filters, the frequency would vary.? The output might
>> drop off, particularly if no filter ws properly selected outside the
>> range where you see output.
>>
>> I think the main symptom is that the frequency does not vary.? Check
>> the VCO output for frequency variation, if the VCOs seem to vayr, then
>> I'd look at the inputs to the mixers.
>>
>> Cheers!
>>
>> Bruce
>>
>> Quoting Radu Bogdan Dicher <vondicher@...>:
>>
>> > ...which doesn't explain the output stuck at 21.5MHz, but at least may
>> > point out what's going on as far as the missing output outside of 14 - <
>> > 20MHz range
>> > Radu.
>> >
>> > On Sun, Sep 18, 2022 at 6:44 PM Radu Bogdan Dicher via
>> <vondicher=
>> > [email protected]> wrote:
>> >
>> >> I was just starting to focus on that, Ozan, as soon as I started
>> perusing
>> >> Service Group L, as per your earlier point here. Thanks a ton for
>> narrowing
>> >> down the scope of the forensics.
>> >>
>> >> To check the validity of this notion, I double-checked specifically the
>> >> 19-20MHz to see if I see output (a bit of a blind spot in my earlier
>> >> measurements), and what do you know... Smoking gun! There's output all
>> the
>> >> way to instrument limit on 19.(9)MHz.
>> >>
>> >> The filtering and associated servos seem to be the culprit here.
>> >> Radu.
>> >>
>> >> On Sun, Sep 18, 2022 at 5:26 PM Ozan <ozan_g@...> wrote:
>> >>
>> >>> It turns out dividers are followed by a bank of filters. 14MHz to
>> <20MHz
>> >>> (exact point is not marked) is one of the filters. It is possible
>> control
>> >>> signals to the filter bank is not functioning. TP1 on the schematic is
>> just
>> >>> before the filter banks. If it is accessible and you could observe
>> TP1, it
>> >>> may help debug.
>> >>>
>> >>> Ozan
>> >>>
>> >>>
>> >>> On Sun, Sep 18, 2022 at 03:29 PM, Ozan wrote:
>> >>>
>> >>> On Sun, Sep 18, 2022 at 10:59 AM, Radu Bogdan Dicher wrote:
>> >>>
>> >>> I got some really weird data to report.
>> >>>
>> >>> I've been playing with adjusting the levels and frequency.
>> >>>
>> >>>? ? 1. It seems I am able to get an output between exactly 14MHz and
>> >>>? ? 19MHz. One half a MHz up or down from there, output drops to zero.
>> >>>? ? 2. As long as there's output (as above), the level adjustment seems
>> >>>? ? to be working OK. I haven't looked closer at whether the value
>> >>> is exactly
>> >>>? ? what it should be, but it raises and lowers as I command it from the
>> >>>? ? AMPLITUDE controls.
>> >>>? ? 3. The frequency doesn't change as I adjust per #1 above. It's
>> always
>> >>>? ? about 21.5MHz (says my scope).
>> >>>
>> >>> Not sure what to make of it yet, but I am going to seek to determine
>> >>> whether this can be triggered by a single module, pull it out and look
>> for
>> >>> damaged caps (first line of defense).
>> >>>
>> >>> Thank you all.
>> >>> Radu.
>> >>>
>> >>> ---
>> >>> Hi Radu,
>> >>> Bruce's reply is the right way to debug. Looking at service manual,
>> over
>> >>> the band of 10MHz-20MHz signal path through dividers look same so
>> output
>> >>> going away just below 14MHz could be something with VCO loop. Output
>> >>> staying at 21.5MHz, not changing is also pointing to the VCO/PLL. I
>> would
>> >>> look at signal coming to J-2 of A2 "divider filter" in Fig 8-L-1.
>> Whether
>> >>> it changes and whether it goes away below 14MHz setting.
>> >>>
>> >>> Do you see any signal out at 2x this frequency, i.e. 28MHz-38MHz range?
>> >>>
>> >>> Ozan
>> >>>
>> >>>
>> >>>
>> >>
>> >>
>> >
>> >
>> >
>>
>>
>>
>>
>>
>>
>>
>>
>>
>
>
>
|
Richard Parrish wrote:
The missing cover won't make a lot of difference in the short term.? Before you go much further, you might try the automatic peaking routine.? Push the shift button and then the peak button and the unit will try to peak itself across the band.? If that doesn't work, you'll have to go thru the full calibration routine for flatness but not anything else.? All that is really required is a scope that can do X-Y display, a crystal detector good to 26GHz and a DVM to begin with.? To confirm the adjustments, you will need a power meter and the proper power sensor.? The procedure works but don't try to take any short cuts unless you've done it before.? To get full power in band 4, the 2-7GHz power amp has to have +27dBm output from 5-6.7GHz.
Richard
Unfortunately the automatic peaking routine is failing. Hopefully I think I have everything except the crystal detector. I will perform the full flatness calibration routine and hope it will solve it, thank you.?
|
8714B Source Fault. (Was Re: Any interest in HP871xA/B/B firmware modification for enabling options?)
Hi.
Regarding the 871x A/B series.
I have a low output level fault in the source module of my 8714B, that has all the hallmarks of a cracked joint or otherwise open cct component somewhere in the RF Source signal path.?? (No errors logged on power up, and the Receivers LO feed is fine.)
I gather that there is (or used to be) an external maintenance extender/jig, that allowed the source or receiver module to be run outside of the main case for maintenance. (I've seen photo's of them on top of the machine, with one side open and exposed.)
Said jig, plugged onto the pins on the rear of the backplane, rather than extending things out of the front of the instrument.
Does anyone in the UK have one I could loan (or even hire for a time!)?
Regards to All..
??? Dave B (G8KBV / G0WBX)
--
Created on and sent from a Unix like PC running and using free and open source software:
|
"Roman Luschik" <romal76@...> writes: I would like to make upper frequency to 26.5ghz
output from my 8340A that can only 20ghz now As already mentioned, the 8340A/B can already do 26.5Ghz. Have you checked what parts you would need to replace? I would expect at least that you need a new SYTM, the output coupler, the detector that is connected to it. Given how rare the SYTMs are, i would expect that it might be easier to sell the Generator, and buy another one. But double check that you have a 8340A, because than you don't need to upgrade anything.
|
Re: HP 400E sticky needle
Indeed, but it is not like we are talking about a high performance bond here. As I understand it, HP developed a machine that drew scales onto an emulsion covered meter card using focused light. More information is available from the patents. Over time, the emulsion dried out, and the relatively weak bond from the emulsion to the white card failed. Just about anything water based would work. But it needs to be slow to set, reversible, and stable. I think milk would be fine. I bonded a ceramic cup, that had a ground flat base, to a highly flat and polished granite countertop with milk (accidentally), and it was very hard to get loose. -Chuck Harris On Thu, 22 Sep 2022 10:00:58 -0700 "Roy Thistle" <roy.thistle@...> wrote: On Sat, Sep 17, 2022 at 05:23 PM, Chuck Harris wrote:
Milk is the original ingredient in white glues such as
Elmer's...
It's a very old glue, made from the phosphoprotein casein (found in
mammalian milk) ... the glue is made by lowering the ph of the milk,
separating the folded protein, and the bringing the ph of the protein
mass back up to cause it to become a thick white liquid. Gesso was
made from it too. It's a tough and water resistant glue, but, pales
in comparison to modern formulations. I don't know what Bordens, or
Elmer, are formulating now. or if if there "white glue" still casein
in it (or if it is only partly casein based) now. (They did add other
'modifiers to "white glue" over the years.) Not sure what is in the
stuff made in China, available from the dollar store.
|
Re: HP 400E sticky needle
Roy,
Is this the program you were referring to?:
Mike
|
??? The 8340A already goes to 26.5GHz unless the stop frequency cal constant has been changed.? The 8341A only goes to 20GHz and cannot be modified easily to go to 26.5GHz.
Richard
toggle quoted message
Show quoted text
I would like to make upper frequency to 26.5ghz output from my 8340A that can only 20ghz now
22.09.2022, 19:16, "Richard Parrish" <richard@...>:
The calibration list is specific to the instrument it was in.? Copying another set of cal constants into another unit is not advisable.? Follow the leveling calibration procedure in the manual, the cal constant starting values can be found in the manual.
Richard
Hello
with my device was a calibration list, in attachment
?
if someone has such from 8340A(B), please send
?
|
Re: HP 400E sticky needle
There is a very good and very flexible free software for printing meter faces (of course you can't print the mirror, if there is one.) With a high res laser or inkjet (ever transfer by dye sublimation) it produces artwork that is very good. The scaling is very good (log or linear is in proportion.)
|
I would like to make upper frequency to 26.5ghz output from my 8340A that can only 20ghz now
22.09.2022, 19:16, "Richard Parrish" <richard@...>:
The calibration list is specific to the instrument it was in.? Copying another set of cal constants into another unit is not advisable.? Follow the leveling calibration procedure in the manual, the cal constant starting values can be found in the manual.
Richard
Hello
with my device was a calibration list, in attachment
?
if someone has such from 8340A(B), please send
?
|
Re: HP 400E sticky needle
On Sat, Sep 17, 2022 at 05:23 PM, Chuck Harris wrote:
Milk is the original ingredient in white glues such as
Elmer's...
It's a very old glue, made from the phosphoprotein casein (found in mammalian milk) ... the glue is made by lowering the ph of the milk, separating the folded protein, and the bringing the ph of the protein mass back up to cause it to become a thick white liquid. Gesso was made from it too. It's a tough and water resistant glue, but, pales in comparison to modern formulations. I don't know what Bordens, or Elmer, are formulating now. or if if there "white glue" still casein in it (or if it is only partly casein based) now. (They did add other 'modifiers to "white glue" over the years.) Not sure what is in the stuff made in China, available from the dollar store.
|
Dave McGuire