Author Topic: Brown custard. (Read 4012 times)

Oilybloke · « **on:** February 23, 2013, 04:55:03 PM »

To aid soap removal, my last 5 batches I have done with the post WBD 7% water wash. The first two were fine, but the last three have turned to custard when the water is added. I am two-staging with KOH, and adding warm water to the bio which is at 70c.

It's recovering o.k. with the addition of meth.

Why is this happening?

nigelb · « **Reply #1 on:** February 23, 2013, 05:08:10 PM »

I've never come across anyone doing WBD and then adding water. This is probably the reason why you're having issues.

You may have had enough methanol left in the first two batches for an emulsion not to form. Probably a more efficient demeth has seen more removed from the bio in the last three.

Under normal circumstances the water is added before any further processes in to help soap removal. Never heard of it being done the other way.

Nige

Dickjotec · « **Reply #2 on:** February 23, 2013, 05:20:49 PM »

I have done a post WBD on and off for some years and never had a problem. I have stopped ATM as I am experimenting with added acetone.
Try reducing the amount of water. How do you add the water, I use the Venturi.
Dick

Julian · « **Reply #3 on:** February 23, 2013, 05:38:50 PM »

I've WBD prior to the 7% wash for years. There's little point in doing it the other way round as the recovered methanol is unusable. I'm still doing it with the titrated acid washes I'm currently trying.

The most logical explanation is an emulsion, which probably means excess soap, which more than likely means excess water somewhere in the process.

I had it recently where I made two distinctly dodgy batches and one of solid soap. I'd adopted a method of drying using ambient air, which worked fine in low humidity but failed miserably in damp weather. Try going right back to basics, meticulously dry the oil and do a HPT, check the SG of your methanol, try new KOH if necessary. Then before adding the 7% wash, take a sample and 7% wash that before going ahead with the main wash.

nigelb · « **Reply #4 on:** February 23, 2013, 05:43:00 PM »

Wel, well, well....having never heard of people post washing after demeth it appears as though many are.

You live and learn

Tony · « **Reply #5 on:** February 23, 2013, 07:09:50 PM »

I used to 7% prewash after WBD when WBD was a new thing to do. Haven't in a long while though - I found it very easy to make jelly if there was a little too much catalyst present. Of course with the Meth still present it is less likely to form a jelly so WBD just increases the odds of disaster.

I've not added water to my batches in any form for years now.

I got the impression water pre-wash was a good way to help with further washing - a headstart as it were - so largely irrelevant to those that just settle.

And besides I'm getting along very well with the lazyman catalyst overdose method - guaranteed to be a disaster if water was added!

Head Womble · « **Reply #6 on:** February 23, 2013, 07:17:57 PM »

I used to add 7% water after WBD and often had this problem.

Sometimes it split by it's self once the pump is off, other times I needed to add some meths.

We think it's due to soaps forming when the water is added, as there is catalyst still present it will react with the bio and water, forming soap.

Oilybloke · « **Reply #7 on:** February 24, 2013, 03:48:10 PM »

Many thanks for your replies.
I am drying the oil by circulation/condenser for at least 12 hours.
Water is sucked in via the venturi.
The last batch I made left 25% unreacted after the first stage, and the previous one to that was 5% after the first stage, so that might suggest it's not a catalyst issue......(perhaps?)

BassAddict · « **Reply #8 on:** February 25, 2013, 04:54:53 PM »

Quote from: Tony on February 23, 2013, 07:09:50 PM

I got the impression water pre-wash was a good way to help with further washing - a headstart as it were - so largely irrelevant to those that just settle.

In winter, every single time I don't do the 5%-7% water pre-wash (I'm not a water washer), i get HMPE's forming. I do sometimes still get very slight HMPEs when I do the pre-wash - but literally nothing to worry about compared to what I get if I don't use the pre-wash.

I'll always pre-wash in winter now and skip it in the summer when HMPEs aren't an issue and can then use the time to reclaim a bit of usable meth from the bio.

Soft top · « **Reply #9 on:** February 25, 2013, 06:06:32 PM »

Quote from: nigelb on February 23, 2013, 05:08:10 PM

I've never come across anyone doing WBD and then adding water. This is probably the reason why you're having issues.

You may have had enough methanol left in the first two batches for an emulsion not to form. Probably a more efficient demeth has seen more removed from the bio in the last three.

Under normal circumstances the water is added before any further processes in to help soap removal. Never heard of it being done the other way.

Nige

I always WBD. But in winter when I do water washing I only reclaim about 1/2 the meths that I reclaim in summer when not water washing. This leaves some meths in the mix that i think helps stop emulsions forming. I call it HWBD--- half whole batch demeth.
I then do 7% pre wash and then go on to water wash.

Oilybloke · « **Reply #10 on:** February 26, 2013, 04:24:10 PM »

With thanks to Soft Top, success! I put back in about 5 litres of meth, then added the water with no problems.

Great stuff, many thanks!

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