As we start to look a little closer at how to clean watch parts, the one thing  heard over and over is not to use IPA alcohol on the pallet fork or the safety roller on the balance. These Jewels are held in place with shellac and shellac will dissolve in alcohol.

 When servicing a movement sometimes it’s more important to know what not to do than it is to know what you should be doing.

 The last thing you want is to create a problem that wasn’t there before you started to service the movement.

 Well today we’re going to put that to the test by soaking pallet forks to see how much exposure to IPA they can take before failure.

We are also going to test vintage pallet forks by running them through an ultrasonic cleaner as well as a rotary machine using professional grade cleaners to see how they hold up.

By the end of this video you will know for sure how not to clean watch parts as well

You will as learn whether it’s safe or not to put a vintage pallet fork in a cleaning machine and this knowledge will make you a better watchmaker.

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Why IPA Alcohol is Great for Rinsing Watching Parts

You know IPA has a lot of appeal for home watchmakers.  It’s relatively safe to use, it has a low odor, and it is relatively inexpensive.

 If you’re using alternatives to professional grade cleaners, IPA also displaces water which prevents corrosion.

Use Only 99% IPA

When I refer to the use of IPA, I’m talking about anything that’s 99% pure or above. I’m not talking about the watered-down versions like 70% IPA or even 91%.

Cleaning Watch Parts: Soaking Tests

 For the testing today I’m going to be using all vintage new old stock pallet forks that are from the same manufacturer. They have the same amount of shellac and are in basically the same condition.

Vintage Pallet Forks
Vintage Pallet Forks

These vintage pallet forks are going to be at least 30 years old and are going to be very typical of what you’re going to find in older movements that you might be servicing.

Testing Procedures

The first test is just going to see if cleaning a pallet stone with IPA on a Q-tip causes any problems with the shellac.

 None of these pallet forks have ever been exposed to IPA.  I’m going to use a different Pallet Fork for each test.  To try to keep the force that I’ll be applying to the stones the same throughout the testing,  I am  going to use an artist brush to see if the stone moves as I move the brush across it.  

Then I’m going to push it lightly with a pair of tweezers while the pallet fork is in a vise. What I’m looking for is I want to see if the stone moves up or down in the slot.

Holding Pallet Fork in Vise
Holding Pallet Fork in Vise

On this pallet fork with no exposure to IPA you can see that neither the brush nor a slight amount of pressure applied with the tweezers causes the stones to move.

Testing with Q-Tip and IPA

Now I’m going to use a Q-tip dipped in IPA.  I’m just going to do a little light cleaning on the stones and then I’m going to test the stones to see if they move at all.

Cleaning with Qtip and IPA
Cleaning with Qtip and IPA

 After a gentle cleaning with the IPA the stones appear to still be stable in their slots with no effect on them whatsoever.

Long Term Effects of IPA on Pallet Shellac

If you’re wondering about the long-term effect of IPA on shellac,  once the IPA evaporates, the shellac will go back to its original hardness.  Similarly, like if you melted shellac with heat.  As it cools, it goes back to its original hardness in about 20 or 30 seconds.

Soaking Pallet Fork for 1 Minute in IPA

 In the next series of tests I’m going to start by soaking the pallet stones in IPA starting for one minute and then I’m going to add one additional minute to the soaking time until we get to the point where the shellac fails and the stone moves in the slot.

 I’m going to select one of the new pallet forks.  I’m going to mount it in a vise and dip it into the IPA for just one minute.

One minute Soak in IPA
One minute Soak in IPA

After 60 seconds of soaking there doesn’t seem to be any visible movement on the pallet stone in the slot meaning that the shellac hasn’t softened enough for the stone to move. The brush is not moving the stone and I’m putting just enough pressure on the stone to cause the pallet fork arm to slightly bend.

Soaking Pallet Fork for 2 Minutes in IPA

Let’s grab a new pallet fork and this time we’re going to soak it for two minutes.

Soaking Pallet fork for 2 Minutes in IPA
Soaking Pallet Fork for 2 Minutes in IPA

 After two minutes of soaking the pallet stone still appears to be stable with the brush moving over it and the shellac is still holding even with light pressure applied with the tweezers.

 I would say this is good as well.

Soaking Pallet Fork for 3 Minutes in IPA

 Now I’m going to grab another pallet fork and this time we’re going to soak it for three minutes.

Pallet Fork after 3 Minute Soak in IPA
Pallet Fork after 3 Minute Soak in IPA

After a three minute soak it has passed the brush test but as you can see a slight amount of pressure with the tweezers has caused one of the pallet stones to fail and move out of its position in its retaining slot.

Testing Results

So, from these tests we have seen that cleaning pallet stones with Q-tips and IPA is totally safe if the shellac is not exposed for too long.

These tests would also suggest that short periods of soaking shellac parts is safe especially if the stones are handled carefully and allowed to dry.

Any exposure over two minutes might be enough to cause the shellac to soften to the point that the stone can be moved in its retaining slot changing its adjustment.

Effects on Pallet forks in Cleaning Machines

99% IPA is a great final rinse because of its purity, the fact that it displaces water and that there’s no residue left behind.

For the home watchmaker who is not using professional cleaning fluids this is pretty important information to know.

Spin Basket Machine

Since soaking them for three minutes in IPA caused failure let’s cut the cycle to two minutes of IPA  flowing over the shellac and see how it handles that.

Rotary Basket Machine
Rotary Basket Machine

 With the pallet fork loaded in a basket, the IPA will be washing over the shellac as the basket spins at a fairly fast rate. Since the shellac on the pallet fork is extremely thin as the IPA flows across the shellac it’s going to start dissolving it.

Pallet Fork coming out of Rotary Basket and IPA
Pallet Fork coming out of Rotary Basket and IPA

 I don’t even have to touch the pallet stone because you can plainly see that the stone is coming out of the slot. clearly you would never want to use IPA as a rinse with any shellac parts in a spinning basket.

 What about the effects of an ultrasonic machine on the Pallet Fork?

 Well if the shellac failed in two minutes in the spin basket, we can expect the same in the ultrasonic Machine.  But what if we used a professional grade rinse instead?  

What I’m going to do is use L&R #3 as the rinse and I’m going to run it for a typical rinse cycle in an ultrasonic of five minutes and I’m going to put two pallet forks in the basket.

Why I don’t Clean Pallet Forks in Machines

 If you have seen enough of my videos you probably already know that I always clean my pallet forks in the balance assemblies separate from all the other parts.

This enables me to take advantage of using IPA as my final rinse. But that is not the only reason.

The main reason is what I’m about to show you.

Ultrasonic machines work because of the tiny bubbles that are exploding on whatever is in the tank which is what is knocking off the dirt and the grime off.   If these bubbles get under the shellac this is what can happen.

Pallet Fork out of Ultrasonic Machine
Pallet Fork out of Ultrasonic Machine

Even when using a professional grade rinse as you can clearly see the pallet stone has come out of the slot.  for most of you this means you’re going to need to source a new pallet fork or this is just going to become a part watch.

Ultrasonic Machines can Loosen Pallet Stones

This is precisely why I recommend not running these vintage parts through any cleaning system no matter whether it’s a basket cleaner or an ultrasonic machine. The chances of the pallet stones separating from the slot are so high, the last thing you want to do is have to start looking to replace the pallet fork.

 Even if you can find one, it’s not always a matter of just dropping it in and having it work like it should. Tolerances in the escapement run in the hundredths of a millimeter.

 If you get a new pallet fork it is common for either the guard pin to be a slightly different length or for the pallet stones to be set at slightly different depths.

 Both issues will screw up one of the safety functions of the escapement. If the guard pin is too short when the watch receives a shock it can cause the impulse jewel to overbank which is going to stop the movement.

 If the guard pin is too long it’ll rub on the safety roller which is going to cause excessive friction, which of course lowers the amplitude.

So anything you can do to avoid screwing up the escapement should be practiced at all times