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Jun 08, 2022 View:

pre bottling filter microns

Has anyone experience with comparing pre bottling filter micron sizes?  I mean the difference between 0.2, 0.5, 1.0 micron cartridges on the final spirit.  I'm wondering if going up to 1 micron will result in any particular (ha see what I did there) difference. 


While I've not bottled spirits myself, I've sold a whole lot of filters. Since there are no takers yet, I'll chime in:

What I hear from customers when they change subtle micron sizes is that there is usually no difference in appearance, but there may be changes to flow rate and filter longevity. It depends on the product, the filter, and how observant or persnickety the user is.

In general, you shouldn't see a difference at submicron levels. Polishing filtration—that is, filtration for appearance—typically happens at > 1µm. Filtration at < 1µm is typically for the reduction of micro organisms. The human eye can't see individual particles smaller than about 70 µm. You can see the effects of a lot of small particles together as haze, which typically means that the product has particles in the 1-5 µm range.

So, you should be able to remove most particulate haze by filtering down to 1 micron. Pretty straightforward…except 1 micron doesn't always mean 1 micron. Depending on the type of filter you're using and the manufacturer, 1 micron may be a "nominal" rating. For example, Brand X may call a filter 1 micron if it removes 90% of particles at 1 micron, whereas Brand Y may call a filter 1 micron only if it removes 99% of particles at 1 micron. So the results you see from filtering at 1µm using Brand X's filters may be different than the results you see using Brand Y's.

Take it all together, and basing filter selection on the experience of other users may not translate to how different filters work for you. I typically advise customers to try a couple of different 10" filters themselves and see if there are any noticeable differences. That's the only way to know for sure.

On the other hand, I've had customers who swear that a 0.65µm absolute final filter gives their product a "Bud Light" brightness that they did not see at, say 1.2µm absolute. Every situation is different…

Anyway, we carry a bunch of filtration stuff for distilleries. Happy to talk to anyone about filtration and their product.


We do a white rum that is treated with powdered softwood carbon for decolorization that requires .1-.22 to remove the gray haze induced by the PAC.  The PAC we use looks like laser printer toner.  I’m sure this has to do with nominal vs absolute ratings - but makes me feel that it doesn’t necessarily hurt to go tighter - assuming you are using two-stage with a pre-filter.

We use the same .1 and .22 with aged spirits - with a 1 or 5 micron prefilter.  Honestly I’ve thrown out cartridges long before they have clogged up, just because I’ve felt I’ve got my money’s worth out of them - and I get paranoid after using them for a few months.

I am of the camp that feels sub-micron filtration really gets you a “sparkle” that really coarse filtration does not (5-20 micron). The decolorization work we did was an eye opener in terms of filter micron ratings.  Even with a decent 1 micron filter - staring down through 200 gallons in a tote - it was obvious.

We used to do a triple cartridge setup with a really coarse initial filter - but came to the conclusion it was a waste of time.

Unless you are going out of your way to kick up barrel char and jam it through t  filters - cartridges last a long long time.  Exception being the decolorization - where we go through multiple carts per batch.


This just in...

I usually use a mori gravity filler with an inline .2 or .5 micron DOE cartridge filter.  I pre filter my batch tanks with a bag filter to remove visible stuff (doing botanical infusions, or char).  But one of my bottles is opaque ceramic, so no way to tell the bottle is full on the gravity filler.  With 3 people we are fast, yes sometimes faster than 750ml out of the gravity filler.

So I recently got an xpressfill volumetric filler, which fills by time.  Set the time and it will fill for that duration.  I connected the same .2 micron DOE cartridge filter before the xpressfill. 

Here's the twist ending:  after filling about 1600 bottles, the fills started to come up short.  Gradually building from a few ml to half a bottle short.  Which was not discovered until over 1000 bottles were short filled.  Because heavy opaque bottle.  I only discovered this because there was too much product remaining in the tank.  Yikes, and a fun way to spend a day, opening sealed cases and bottles to refill them to correct volume on the gravity filler.

I traced the underfilling issue to the .2 micron filter by process of elimination.  The filter looked almost as pristine white as when new.  It seems the pump on the xpressfill is slowing down with the tiniest additional pull from the barely used filter.  This is completely unexpected because I previously used an xpressfill for a few years with a .5 micron DOE cartridge inline.  So apparently going from .5 to .2 micron is a big no for the xpressfill volumetric filler.

btw, I used that same .2 filter to finish the opaque bottle run on the gravity filler without issue.


Ah ok - sucking through a filter is a lot harder on the pump than pushing.  I'm talking about tank-to-tank filtering prior to bottling.  And timer fill is going to be far more sensitive to changes to input flow rate.

We use a tall bottling tank, we need to adjust the fill time of our volumetric over the course of the run as the level in the tank falls.  It's most noticeable once the level falls below the level of the filler.  We picked up a Mori just because of how frustrating the fill rate adjustments were.

Reply:6 hours ago, Silk City Distillers said:

Most pumps we use can’t generate the same differential in suction as they can on the output side.

Enolmatic is vacuum, totally different scenario.


Reply:6 minutes ago, Silk City Distillers said:

You can pull through filters, but unless there's a compelling reason to do so, it is less efficient than pushing through them, and there are some strong arguments against pulling through filters.
Some positive displacement pumps can pull excellent vacuum—air diaphragm or peristaltic pumps, for example pull a very strong vacuum. However, even a "perfect" vacuum (which isn't possible to achieve on earth) is only about 14.7 psi. Most filters are not considered clogged until they reach about 35 psi of pressure differential

So, you definitely can pull through filters. It may work perfectly fine for some applications, particularly if the filtered product has very low solids and isn't likely to clog up the filter anytime soon. However, you will be leaving filter lifespan on the table since your filters will be clogged at less than half their usable life.

Also, finding vacuum leaks is no fun. I'd rather try to diagnose a leak under pressure than under vacuum.

Anyway, this is all academic. If you're filtering tank-to-tank and you're using a pump, you should definitely put the filters after the pump and push through the filter. Pulling through the filter increases the risk of pump cavitation and dry running. The enolmatic is a vacuum filler, so no choice there, and no harm, really. The upside for the Enolmatic vendors is that they get to sell more filters since the filters will necessarily be considered clogged more quickly. Since the Mori Filler is not a vacuum filler, we always put the inline filter after the pump.

3 hours ago, Silk City Distillers said:

I think we are saying the same thing.

Pump slip on most displacement pumps makes pulling that kind of vacuum a long shot.

Reply:On 2/27/2020 at 2:56 PM, MichaelAtTCW said:
Reply:22 hours ago, Silk City Distillers said:
Reply:3 hours ago, bluestar said:
Reply:21 hours ago, MichaelAtTCW said:
Reply:52 minutes ago, bluestar said: