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Pitch lap trouble

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#1 Aquarius Of The Night

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Posted 13 January 2018 - 11:11 PM

Ok, so I poured and re-poured a pitch lap several times because each time there was a defect that I didn't like in it.  I poured the most recent one about an hour ago while looking better than the other 3 that I poured(I recycled the pitch don't worry) I still had some defects in the pitch lap.  Repouring it again isn't an option as it is 40 degrees outside and my family is claiming that the smell is giving them headaches. First I am asking if I should really worry about the surface and if I need to reshape it how should I go about softening the pitch enough to give enough to reform but not stink the whole house up?  

https://imgur.com/a/GrpDO



#2 mark cowan

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Posted 13 January 2018 - 11:30 PM

Boiling hot water will soften it enough to repress it with the mirror (preheated!).  It won't smell too much, but hot pitch smells bad, some people claim...


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#3 Aquarius Of The Night

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Posted 13 January 2018 - 11:33 PM

Boiling hot water will soften it enough to repress it with the mirror (preheated!).  It won't smell too much, but hot pitch smells bad, some people claim...

To me it kinda smells like cherries 



#4 mark cowan

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Posted 13 January 2018 - 11:44 PM

Swedish pine forests in the morning, with dew.  ;)



#5 Pinbout

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Posted 14 January 2018 - 07:34 AM

I use hot tap water, I’d never use boiling water, since you need to touch by sticking you hand in the water. #scalding 


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#6 Augustus

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Posted 14 January 2018 - 09:11 AM

Looks fine to me. Just get a razor blade/knife and trim the edge, then cut some channels, and then go crazy scratching random microfacets all over it.

 

 

Boiling hot water will soften it enough to repress it with the mirror (preheated!).  It won't smell too much, but hot pitch smells bad, some people claim...

To me it kinda smells like cherries 

 

Interesting, what kind are you using? Looks like Gugolz, which honestly reminds me of the smell of burning electronics/plastic.

 

Swedish pine forests in the morning, with dew.  wink.gif

Only Burgundy pitch smells remotely like pine trees. Gugolz is made from petroleum.


Edited by Augustus, 14 January 2018 - 09:18 AM.

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#7 Aquarius Of The Night

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Posted 14 January 2018 - 09:13 AM

My tap water comes out at about 120 degrees.  I tried reforming it a little last night with hot tap water and it moved it a little but not a whole lot. 



#8 Aquarius Of The Night

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Posted 14 January 2018 - 09:15 AM

Looks fine to me. Just get a razor blade/knife and trim the edge, then cut some channels, and then go crazy scratching random microfacets all over it.

 

 

Boiling hot water will soften it enough to repress it with the mirror (preheated!).  It won't smell too much, but hot pitch smells bad, some people claim...

To me it kinda smells like cherries 

 

Interesting, what kind are you using? Looks like Gugolz, which honestly reminds me of the smell of burning electronics/plastic.

 

Swedish pine forests in the morning, with dew.  wink.gif

Only Burgundy pitch smells remotely like pine trees, and that stuff is useless. Gugolz is made from petroleum.

I am using Burgundy.  And I will agree with him that is has the smell of pine.  Why is it useless?  I had that box full of grinding materials and I have several pounds of Burgundy and only a couple of small cups full of Gugolz at least I think thats what it is because it isn't labeled.



#9 Augustus

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Posted 14 January 2018 - 09:18 AM

My tap water comes out at about 120 degrees.  I tried reforming it a little last night with hot tap water and it moved it a little but not a whole lot. 

It's not going to move a whole lot. I'd just trim the edges and carve in the facets; it's fine.

 

 

Looks fine to me. Just get a razor blade/knife and trim the edge, then cut some channels, and then go crazy scratching random microfacets all over it.

 

 

Boiling hot water will soften it enough to repress it with the mirror (preheated!).  It won't smell too much, but hot pitch smells bad, some people claim...

To me it kinda smells like cherries 

 

Interesting, what kind are you using? Looks like Gugolz, which honestly reminds me of the smell of burning electronics/plastic.

 

Swedish pine forests in the morning, with dew.  wink.gif

Only Burgundy pitch smells remotely like pine trees, and that stuff is useless. Gugolz is made from petroleum.

I am using Burgundy.  And I will agree with him that is has the smell of pine.  Why is it useless?  I had that box full of grinding materials and I have several pounds of Burgundy and only a couple of small cups full of Gugolz at least I think thats what it is because it isn't labeled.

 

Forgive me, my only experience with Burgundy pitch was this terrible old maple-colored stuff. Yours seems like it's fine. 



#10 Aquarius Of The Night

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Posted 14 January 2018 - 09:29 AM

 

My tap water comes out at about 120 degrees.  I tried reforming it a little last night with hot tap water and it moved it a little but not a whole lot. 

It's not going to move a whole lot. I'd just trim the edges and carve in the facets; it's fine.

 

 

Looks fine to me. Just get a razor blade/knife and trim the edge, then cut some channels, and then go crazy scratching random microfacets all over it.

 

 

Boiling hot water will soften it enough to repress it with the mirror (preheated!).  It won't smell too much, but hot pitch smells bad, some people claim...

To me it kinda smells like cherries 

 

Interesting, what kind are you using? Looks like Gugolz, which honestly reminds me of the smell of burning electronics/plastic.

 

Swedish pine forests in the morning, with dew.  wink.gif

Only Burgundy pitch smells remotely like pine trees, and that stuff is useless. Gugolz is made from petroleum.

I am using Burgundy.  And I will agree with him that is has the smell of pine.  Why is it useless?  I had that box full of grinding materials and I have several pounds of Burgundy and only a couple of small cups full of Gugolz at least I think thats what it is because it isn't labeled.

 

Forgive me, my only experience with Burgundy pitch was this terrible old maple-colored stuff. Yours seems like it's fine. 

 

My pitch is pretty old as well.  The grinding kit was made back in the 80's but everything else is still in great condition.  Heck the box hadn't been opened from the company since he had received it.   


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#11 ccaissie

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Posted 14 January 2018 - 10:01 AM

Burgundy pitch is from a spruce, not a pine.  Here in Maine, you must know "which trees make shingles"...in other words you gotta know your stuff.

 

I make my own pitch lap material out of burgundy pitch, which is a bit too soft, rosin, and talc as a filler.  

 

There are volatiles that evaporate over time, so old laps and pitch supplies tend to get harder, though I doubt that an unopened container of pitch has really changed that much.   ATM info abounds on tempering the pitch.  For my use, the talc makes the pitch hold its shape, while the actual surface is soft. When I do sub lap work, I use straight pitch, which is quite soft, and press/test often.

 

My wife loves the smell...though I melt mine on a hot plate very slowly so I'm not smokin' the place up.  A double boiler setup should work for you...pitch at 180 is pretty liquid.

 

If you've got gross surface defects on your lap, you can drip pitch drops to fill them.  A couple sessions of warming and alternate pressing with window screen and the mirror will get you where you need to be.  A perfect lap surface is an ideal, but practically, not crucial.  It should be visibly even.  Randomness, blending and a good understanding of stroke effects are more important. 


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#12 Mike Lockwood

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Posted 14 January 2018 - 11:58 AM

To heat a lap for re-shaping, the best way I have found is to suspend some heat lamps over it while the mirror is rotated underneath.

 

Do not leave it unattended.  Keep the lamps ~8-16" inches away from the surface (depending on the pitch).



#13 pjmulka

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Posted 14 January 2018 - 01:48 PM

I use a dollar store fire starter right after I pour the pitch to
1- take care of bubbles.
2- work any problem areas out.

Just a second of flame gets the area flowing enough to self level.
I've seen people use little trigger tourchs and I'm sure that's much easier but I don't have one.

Before I started using the fire starter I pressed some just hideous laps into submission using hot tap water, a lot of weight and time.
Just warm press the crap out of it and you'll be fine.

Polish more, worry less!

One little bit of wisdom I learned the hard way.......you may need to press for long time and that's ok however, every 20-30 mins you need to take the weight off move the mirror around and make sure the lap is wet! If the lap gets to dry the mirror will lock onto the lap and it's not fun trying to get them apart!

Good luck! And don't get discouraged my first mirror I messed up the lap in every way there is to mess up a lap. In fact I had start from scratch......like make a new plaster disk from scratch more the once but I ended up with a great figure on a mirror that's far better than any mass produced mirror I've seen.

Don't give up!
-Pete.

#14 dave brock

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Posted 14 January 2018 - 01:57 PM

However you heat the lap (I use hot tap water), you'll find it presses far quicker if you cut the 

facets first. You may need to retrim them once or twice before the lap fully matches the mirror.

 

Dave


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#15 dave brock

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Posted 14 January 2018 - 02:04 PM

One little bit of wisdom I learned the hard way.......you may need to press for long time and that's ok however, every 20-30 mins you need to take the weight off move the mirror around and make sure the lap is wet! If the lap gets to dry the mirror will lock onto the lap and it's not fun trying to get them apart!

When working a mirror I often leave the lap on the mirror (whichever is lighter goes on top) between polishing spells (sometimes a couple of days) with plenty of cerium mix between. They are covered with a wet towel and topped with a sheet of plastic. Never had one dry out. Of course this is cold pressing only.

 

Dave


Edited by dave brock, 14 January 2018 - 02:06 PM.

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#16 pjmulka

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Posted 14 January 2018 - 02:31 PM

Here is a early train wreck I call the anti-pitch lap. Note the:

Enormously wide and irregular channels - that's bad

Irregular length and width of the facets- that's bad

Lack of micro-facets - that's bad

poor beveled edge- that's bad 

Anti pitch lap3.jpg

 

The photo in the next post is much better

Note the:

Thinner channels of equal width and depth - that's important. It's also important that the channels are V shaped

 

The facets [squares] are equal width and length - that's important 

 

The facets have micro-faciets this can be done several ways but the pitch needs someplace to imbed it's self to do any work- that's important

 

Lap edge has good bevel - that's important

 

Also maintain your lap, maintain your lap, maintain your lap! You accomplish this by:

 

1. Always always always stay in good contact. Press early press often when in doubt press.

 

2.The channels must stay open

 

3.(I'm going to get yelled at for this) maintain your micro-faciets. If you can't feel the texture on your lap your not polishing. I'm pretty sure I first heard that  from the man himself in a youtube video.

 


Edited by pjmulka, 14 January 2018 - 02:34 PM.


#17 pjmulka

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Posted 14 January 2018 - 02:33 PM

Sorry I guess you can't see the bevel in this photo.....but it's there. :)

better pitch lap.jpg



#18 Pinbout

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Posted 14 January 2018 - 02:35 PM

 

Sorry I guess you can't see the bevel in this photo.....but it's there. smile.gif

we stopped bevelling the pitch at delmarva and cut it straight down. otherwise its a subdia polisher

 

nice looking pitch polisher


Edited by Pinbout, 14 January 2018 - 02:35 PM.

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#19 pjmulka

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Posted 14 January 2018 - 02:40 PM

 

One little bit of wisdom I learned the hard way.......you may need to press for long time and that's ok however, every 20-30 mins you need to take the weight off move the mirror around and make sure the lap is wet! If the lap gets to dry the mirror will lock onto the lap and it's not fun trying to get them apart!

When working a mirror I often leave the lap on the mirror (whichever is lighter goes on top) between polishing spells (sometimes a couple of days) with plenty of cerium mix between. They are covered with a wet towel and topped with a sheet of plastic. Never had one dry out. Of course this is cold pressing only.

 

Dave

 

Ya I've only had them lock while pressing with heavy weight for hours at a time without rotating the mirror.



#20 mark cowan

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Posted 14 January 2018 - 03:04 PM

I use hot tap water, I’d never use boiling water, since you need to touch by sticking you hand in the water. #scalding 

Depends on how much you need to adjust.  The water is to heat it up, you leave it sit until you can handle it if you need to.  Wear nitrile gloves if you don't want hot pitch sticking to your skin.  Hot tap water is fine for warm pressing but major adjustments need more softening.  :shrug:



#21 mark cowan

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Posted 14 January 2018 - 03:06 PM

Only Burgundy pitch smells remotely like pine trees. Gugolz is made from petroleum.


No it's not.  But some are.  Gugolz used to smell nice (like the Swedish pines it came from) when you cracked open a new tube, but they changed the formula some years ago and made it work not as well.  Still a tree product:
 

PROVIDENCE, RI (PRWEB) JUNE 06, 2017

Meller Optics, Inc. has introduced a full line of optical polishing pitch that comes in five hardness grades and can be easily mixed for precisely lapping virtually any optical material.

Gugolz Optical Polishing Pitch from Meller Optics comes in five grades from very-soft to very-hard with melting points from 52°C to 87°C, and is ready to use without screening, filtering, or mixing additives. All five hardness grades are fully compatible, allowing users to simply slice the amount required, melt, and pour to achieve their desired hardness grade.

Made from all-natural wood resin rather than petroleum byproducts, Gugolz Optical Polishing Pitch helps prevent contamination of the polishing media and substrates. Ideally suited for blocking, lapping, and polishing, it can be used for applications with CaF2, germanium, quartz, ZnSe, ZnS, silicon, and other optical materials.


Edited by mark cowan, 14 January 2018 - 03:20 PM.

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#22 Aquarius Of The Night

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Posted 14 January 2018 - 03:21 PM

This is my pitch lap with the mirror 

20180114 144411
20180114 144403

 


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#23 Ed Jones

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Posted 14 January 2018 - 03:29 PM

 

 My pitch is pretty old as well.  The grinding kit was made back in the 80's but everything else is still in great condition.  Heck the box hadn't been opened from the company since he had received it.   

Burgundy pitch was sold in cardboard containers and if it's from the 80's it has likely lost much of its solvent an is way too hard. What does the thumb-nail test show?  You may need to make a pitch hardness tester.  These videos might help:

https://www.youtube....h?v=H-GzbR69MzU

https://www.youtube....h?v=H-GzbR69MzU


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#24 dave brock

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Posted 14 January 2018 - 03:36 PM

With 5-10min polishing, if the lap is in good contact and is well mixed, it should become even coloured all over.

If the large dark area stays then something is not right.

 

Dave 



#25 Aquarius Of The Night

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Posted 14 January 2018 - 03:37 PM

if my thumb can make a dent is it good?




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