I am thinking of picking up one of the latest model VST refractometers for my own personal coffee geekery. I have a couple questions before committing, though.

Is there any reason to get the ExtractMojo software if I am planning to use the MojoToGo app? From what I gather MojoToGo has all the necessary functions, but doesn't have the charting report feature of the full ExtractMojo software.

The syringe filters VST sells are rather expensive. There are a number of inexpensive sources for Luer-Lok syringe filters, but I'm unsure what diameter, material, and pore size are appropriate. I know there is a cheap DIY solution of just using Aeropress filters, but I would prefer the syringe filters if possible. Does anyone know the correct specs?

e: Answering part of my own question, the pore size specification appears to be 0.45µm based on this post, but I'm still unsure of diameter and most appropriate material (nylon, PTFE, etc.).

There are a number of inexpensive sources for Luer-Lok syringe filters, but I'm unsure what diameter, material, and pore size are appropriate. I know there is a cheap DIY solution of just using Aeropress filters, but I would prefer the syringe filters if possible. Does anyone know the correct specs?

Hi Bob. The paper filters used for aeropress are std coffee filter paper, intended for filtering coffees ground to a much more coarse grind, and are effective to ~2.2µm. This is adequate for drip coffee when used with the coffee refractometer, or for press-pot coffee where the grind particle sizes are quite large.

In order to remove the fine particulate in coffee ground for espresso, to a level of clarification that does not cause erratic or inaccurate refractometer readings, you need a 25mm syringe filter with integrated pre-filter which prevents premature clogging. The filter needs to remove particles larger than 0.589µm. The filter also needs enough headroom (inside the filter housing) for particulate to build up w/o clogging. Finally, the filter housing structure and fabrication must not allow sediment to bypass the filter media under high pressure. This takes several staggered layers of media and high quality design and manufacturing of the filter.

The GE/Whatman GMF series meet these specifications:
Part No. 6870-2504 (Qty 150) or 6871-2504 (QTY 1500). Or
6876-2504 (Qty 150) or 6905-2504 (QTY 1500)

A short video is here: http://www.whatman.com/References/gdx.mpeg

The syringe filters VST sells are rather expensive.

Expensive relative to what? The cost of the coffee spent w/each measurement? The cost of the filter paper?

After you thoroughly research the best prices you can get on the GMF filters ($3.50-$4.50ea), I think you'll find the VST filters quite reasonable (~$1.29ea). VST purchases a custom configured filter in 25K QTYs in order to get the price to what we think is a reasonable level, relative to what else is available. They are sold at near cost, even though the health care industry has pushed prices to record highs for syringe filters in general. Remember, most users won't need to measure every shot, rather, just those shots used for trouble-shooting a problem. Given the cost of typical specialty coffee, these days, at $15-$16 USD/12-oz, that equates to about $1/shot, for a 21-g dose. If a data session solves a problem, in my view, it's well worth the cost if the espresso is greatly improved afterwards.... These can be used to find and segregate out faulty filters, adjust hard mineral and TDS of soft water for proper extraction, confirm if a coffee is fully versus under-developed at roast, and a range of other extraction related problems.

Is there any reason to get the ExtractMojo software if I am planning to use the MojoToGo app?

Re> MoJoToGo and ExtractMoJo, you're correct. eMoJo provides a graphical representation, which many users find helps to visualize the data. A picture is worth a thousand words, as it were, and you can save (as PNG, BMP, JPEG) the charts and data for later viewing. But eMoJo also allows you to plot an entire data session onto a single graph, and add notes. This is very helpful when you're performing numerous careful comparisons, and is a visual way to display comparative data, versus a table of numbers. The images and charts can be embedded into documents or presentations as well. The data for measurements can be emailed to MoJoToGo, and saved there [in the MoJoToGo database] as well.

I am thinking of picking up one of the latest model VST refractometers for my own personal coffee geekery.

The new LAB Coffee instrument has a number of beneficial features, but HB does not allow commercial posts, so please check the web site. Most noteworthy are double the precision and accuracy, backlit alphanumeric display, and a more rugged design (intended for LAB or field use) using sapphire optics and stainless steel sample well that is faster and easier to purge and clean between uses. Happy brewing-Vince

MoJo wrote:The new LAB Coffee instrument has a number of beneficial features, but HB does not allow commercial posts, so please check the web site.

When a member asks a question that cannot reasonably be answered from another source, it's perfectly legitimate and appreciated that the vendor respond. Another exception to the "no commercial posts" rule is made for those searching for a difficult-to-find part. In that case, a response from a vendor having said part is rendering a service to the HB community. In short, the primary purpose of the "no commercial posts" rule is to avoid an open question resulting in the poster being bombarded by sales pitches.

If you or any other vendor has questions/concerns about this policy, your are welcome to contact me. Having moderated forums for many years, I have no difficulty recognizing the difference between vendors who want to inform versus those who only want to sell.

Thank you for the detailed information about the filters you carry. I was aware that syringe filters are pretty expensive in general, but there are significantly cheaper (Asian) sources (e.g. here), and I wasn't sure why they would be inappropriate for this purpose until reading your reply.

MoJo wrote:Expensive relative to what? The cost of the coffee spent w/each measurement? The cost of the filter paper?

Well, to me, it's more that the minimum quantity is 100, and it's difficult for me to justify spending $130 on filters up front when I'm not sure how much I will even use the refractometer for espresso. If you sold a 25 pack at a slightly higher per unit price I would probably have just ordered that without thinking about it so much. Is it possible to get the "Syringe Filter Kit (25 coffee filters/5 syringes)" that comes with some of the bundle options separately?