8 replies to this topic

[elliotwoods]

Thank you all for the help so far with our large optical flat project:

https://www.cloudyni...y-flat-project/

 

 

One concern we have now is buying 72 lbs / 32 kgs of optical pitch

Ideally I'd like to see if there's a way to buy this in bulk to make it more affordable, but I can only see suppliers dealing in small quantities at the moment. As you can imagine - this then becomes extremely expensive.

 

Is it possible that anybody has any contacts who might be able to deal in these larger quantities? e.g. even with the manufacturers themselves? Or perhaps are there other trade names that are used when purchasing industrial quantities?

 

Thank you

Elliot

 

 

[dogbiscuit]

Meller Optics Inc.

https://melleroptics...olishing-pitch/

 

Call them for bulk pricing.

[Ed Jones]

This may help.

[elliotwoods]

Thank you!

I've emailed Meller (on a different time zone here)

 

Also - yes was wondering about a DIY approach

That thread is archived now. I'd be really interested to know where @Curiosis found the information, and specifically recipes for pitch that have different levels of hardness.

I was hoping that we could just buy pine pitch and use that, but it seems that the principle ingredient is tar/rosin and then other ingredients need to be added with experimentation to achieve the correct hardness.

 

Also this thread is interesting for DIY pitch:

https://www.cloudyni...-for-polishing/

Edited by elliotwoods, 09 March 2021 - 03:19 AM.

[Oregon-raybender]

Here you go.

 

Starry Nights

 

http://www.universal...65/Default.aspx

[elliotwoods]

thanks again @Oregon-raybender

Hope you're well!

 

We contacted Universal Photonics Korea, and they quoted a particularly high cost (e.g. higher than buying lots of small quantities from First Hand Discovery + import costs). However, that was Universal Photonics Korea, so local vendor costs are added on. 

(if it is impolite to share that type of information here then I will take that down).

 

 

 

I've also come across mention of a 'paper lap', e.g.:

https://en.wikibooks...g#The_Paper_Lap

Which is possible when your tool has a shape that matches your mirror.

In our case we're going with the 3-flats method, so the other flats are the tools for the grinding stages, and they do 'match the mirror'.

So perhaps there is a way to continue to use the glass flats against each other for the polishing stage also

(e.g. with a paper lap in-between)?

Edited by elliotwoods, 09 March 2021 - 05:48 AM.

[Nodda Duma]

Meller Optics for bulk Gugolz polishing pitch.
Universal Photonics for all their stuff (including Gugolz). You may want to contact their US office and explain the pricing issue. Then again, you may have to re-evaluate what you’re trying to do if you’re worried about the price of pitch

Alternatively, you can look at felt pads for the bulk of your polishing and finish with pitch (not advisable if you need a smooth surface finish tho).

As mentioned above, you can also mix your own from bulk ingredients. Nothing wrong with that.

Edited by Nodda Duma, 09 March 2021 - 06:25 AM.

[ccaissie]

I don't know where Stan Brower (Laboratory Optical, Plainfield NJ) bought his pitch/rosin but he brewed his own, and that's what I use.  I inherited a bunch of the pitch, a big box of rosin and talc from Fischer chemicals.

 

I just sent out a pound of the blend to a guy who was looking for good old burgundy pitch. 

It's Burgundy pitch, Rosin and talc.

Mixed up a batch and sent out a couple small tubs this a.m.

 

Recipe:

4 lbs Burgundy Pitch

12 oz.Rosin

4 cups talc

 

The talc is a filler to give the pitch a stiffness for production machine polishing, and the base Burgundy/rosin is in proportion to give it a softness for fine polishing.  Wood flour  or even wheat flour is said to be a suitable filler.

 

 I think it's just great for all the stuff I do...Newtonian mirrors.  I have some remelted with Gugolz 82 that I use for flats, but Brower used his blend for all his flat work.

 

Oh yeah, Post #4 has a link to pitch ideas and which mentions using HCF Honeycomb foundation  Pretty good sized sheets of Beeswax with texture.  Should be available wherever there's a beekeeper..  Not the best for the final polish, but can get the job done pretty fast.   https://www.amazon.c...r/dp/B07V6Z54P8

Edited by ccaissie, 10 March 2021 - 12:07 PM.

[elliotwoods]

Eventually we settled on Meller optics with Gugolz pitch.

We didn't find a really cost effective way to get the raw materials here, and I'm concerned that it's one more thing that would need controlling (given that so many other parts of the process are quite new all at once).

 

 

@Nodda - 

don't worry - already too late to re-evaluate

 

@CCassie -

Thank you for sharing this recipe! It sounds very straightforward, and good to know that you've had success with it.

I might revisit this later, but for now I'm going to go with the pre-made this time.

 

 

Thanks all for the help!