High Temperature Tools & Refractory


Inswool questions

Satanite questions

APG #36 questions

Bubble Alumina questions

Soft Firebrick questions

Hard Firebrick questions

Sairbond questions

Insboard questions

ITC-100 questions

ITC-213 questions

Nelsonite questions

Castable Refractory Questions

Mizzou questions

Kast-O-Lite 30 LI

Ceramic Platen Liner questions

Wire Rope questions

Venturi burner questions

Forced Air Burner questions

Propane Regulator questions

POL fitting questions

Needle Valve questions

Ball Valve questions

Forge questions
 
Etcher questions

Hydraulic Press questions

Wire Rope questions

InsTuff questions

Gate Valve questions

MIG Tip questions

Sch. 80 pipe nipple questions

Ward Tee questions

Wrought Iron questions

Heat Treating Salts




Inswool questions

How thick should I line my forge with Inswool?

The more insulation you have in your forge the better, to a certain degree.  A 1" layer is generally enough for most forges, however, adding 2" and even 3" can significantly increase the efficiency of your forge.  A more efficient forge uses less fuel and costs less in operating costs.  The tradeoff is you have higher initial lining costs.  A limiting factor is the size of your forge shell.  You do not want to make your forge chamber too small such that the burner flame impinges directly on the work piece if possible, be sure to leave enough room for proper burner positioning.

Do I need to coat the fibers in the Inswool with anything?

Yes, Once you have the Inswool liner in place, you will need to top-coat it with Satanite and/or ITC-100 to protect the liner as well as stabilize the fibers in the ceramic fiber blanket once the forge is in use.  Inswool does not present any dangers to the user when lining the forge, other than an irritant much like fiberglass.  However, upon heating to temperatures above about 1600 degrees F, free silicates can form that you do not want to breathe.  Top-coating the fiber with Satanite and/or ITC-100 seals the Inswool and keeps everything in place.  If at any point you poke a hole in the Satanite/ITC-100 top-coating, you'll want to patch the hole with some more Satanite.  Also, at some point in the future when you reline your forge, be sure to wear a respirator, gloves, and long sleeve shirt and try to directly dump the lining into an empty trash bag and seal it off.  The dangers probably aren't as great as that last sentence may sound, but it's always better to err on the side of safety. 

You should topcoat the Inswool with something like Satanite or ITC-100, or you could use a rigidizer such as InsTuff.  We generally recommend a basecoat of 1/4" of Satanite and then a topcoat of ITC-100.  This provides a more robust coating with the added efficiency obtained from the use of ITC-100.  Generally, for most forges, a five pound bag of Satanite and a half pint of ITC-100 is sufficient.

More info coming soon!



Satanite questions

How do I mix and apply the Satanite?

Mix the Satanite to a thick paste...just keep adding water slowly until you get a pasty consistency that you can paint on with a paintbrush....roughly the consistency of sour cream.  Spray the ceramic fiber insulation down using water with a hand sprayer to wet it lightly.  Next, apply the Satanite to the wool using a paintbrush, covering all exposed wool surfaces.  To cure it, you want to dry it slowly.  First, let the forge sit for a few hours minimum to air dry a little, then fire up the forge just briefly and shut it down.  Do this several times, allowing it to cool down in between and increasing the on-time with each subsequent cycle.  You'll see water vapor evaporating the first few times you do this.  Finally, fire it up and bring it up to full temp to fully cure it.  You will probably want to apply at least two coats of Satanite in this manner...it's a little time consuming (do it over a couple of day period) but makes for a more robust coating.  a 1/4" layer is a good thickness to shoot for.  If you are going to apply ITC-100 over top of the Satanite, be sure to fully cure the Satanite first.

Can I use Satanite for clay coating my blades to produce a hamon?

Yes,  Satanite and APG #36 are two of the most commonly used "clays" used in the U.S.A. for clay coating knife blades.

What else can I use Satanite for?

You can apply a thin wash of Satanite over your entire blades to aid in keeping scaling to a minimum while heat treating.


APG #36 questions

Which is better for clay coating, Satanite of APG #36?

There is no real answer to this question.  About 50% of our customers prefer APG #36 and 50% of them prefer Satanite!  It really just depends on your preferences, try a little of each to see what works best with your methods. 

How do I mix and store the APG #36?

APG #36 comes premixed.  You apply it to your blade directly from the can, you do not need to mix it with water (unless you just want it a little more thin).  For storage, keep it in a cool airtight container, such as the one it came in.  In addition, you can top up the container with water to keep the clay from drying out.  Just pour off the water before your next use. 

What is the best way to cure APG once it has been applied to the interior of the forge?

Allow it to air dry until a hard set develops and then fire the forge up slowly to cure it (See Satanite directions).

How many coats do you recommend for using APG#36 as a ceramic fiber blanket coating (Inswool)?

I recommend several thin coats to build it up to about 1/4" thickness.  This just adds a little more robustness to the forge liner.  All you have to have is a thin wash to stabilize the ceramic fiber blanket.

Can itc-100 be applied to it afterwords?

Absolutely, and I recommend it.  Follow the directions as outlined in the ITC-100 section of this FAQ.


Bubble Alumina questions

How do I mix/apply the Bubble Alumina?

Mix the Bubble alumina to a troweling consistency and trowel it in place onto dampened Inswool ceramic fiber blanket  Let it dry for a few hours and then slowly fire up your forge to fully cure it.  This is one of the most flux resistant coatings we have found, I'm sure you will be very pleased with it! 

What thickness coating do you recommend for the Bubble Alumina and how do I figure out how much to order?

I generally recommend a coating of at least 3/8" on the floor of a horizontal or vertical forge.  The Bubble Alumina we carry has a density of about 86 pounds per cubic foot.  So what you need to do is to figure out the surface area of the Inswool you want to coat.  Then take this value of the surface area and multiply it by the thickness of the coating you want to apply and this result gives you the volume of the coating you want to apply.  If your measurements are in units of inches, you'll need to convert your volume from cubic inches to cubic feet.  Once you have the value of the coating volume, you can multiply this number by the density of the material (86 pounds per cubic feet) and the result will be the amount of material in pounds you will need to acheive the coating at the thickness and surface area you specified. 

Let's illustrate this with an example.  Let's say I have an 8" diameter horizontal tube forge that is 12" long and I want to coat the floor with Bubble Alumina 1/3 of the way up the side walls because I'm only worried about flux that falls off of the billet and lands on the floor, which will immediately degrade my liner (Inswool).  Also, lets say that I put 1" Inswool in the forge and also have 1" Inswool in the front and rear of the forge.  This now makes my actual forge chamber 6" diameter x 10" long.

1)  First lets calculate the total surface area of the Inswool liner:  total area = Pi * (Diameter)^2 * (1/4) * length

Plugging in the numbers we have:  total area = (3.14159) * (0.25) * (6")^2 * (10") = 282.75 square inches = Approx: 283 square inches (Always round up).

2)  Now if we only want to coat the liner about one third of the way up, we only want to coat 1/3 of the total surface area calculated in step (1), thus multiply the result in step (1) by 1/3.

area to cover = (1/3) * total area

area to cover = (0.33333) * (283) = 94.333 = approx: 95 square inches.  (Alway round up).

3)  If we want to apply a coating that has a thickness of 3/8", we multiply the "area to cover" by the thickness of the coating we wish to apply and the result is the total volume of the coating:

volume of coating in cubic inches = (area to cover) * (thickness of coating)

volume of coating in cubic inches = (95 square inches) * (0.375 inch) = 35.625 cubic inches = approx: 36 cubic inches

4)  Now that we have the volume of the coating in cubic inches, we need to convert it to cubic feet.  There are 1728 cubic inches in a cubic foot, thus we need to do the following calculation:

Volume of coating in cubic feet = (1/1728) * (volume in cubic inches)

Volume of coating in cubic feet = (1/1728) * (36 cubic inches) = 0.020833 cubic feet = approx: 0.021 cubic feet

5)  We're almost done!  :)  Now take the value of the volume of the coating and multiply it be the density of the material and you have the amount you need in pounds:

Amount needed in pounds = (density of material) * (volume of coating in cubic feet)

Amount needed in pounds = (86 pounds per cubic foot (for Bubble Alumina)) * (0.021 cubic feet) = 1.806 pounds = approx: 1.81 pounds

6) Notice I always round up a little in my calculations.  You don't want to be caught with too little material when you go to line your forge, a little too much is ok, but a little too little is not good!  Also, always add in a little for waste and such.  So, if I were going to line a forge with the above dimensions in this example, I would order a 2.5 bag of Bubble Alumina.


More info coming soon!


Soft Firebrick questions

How do I make a single brick forge?

Take a look at the Forge Gallery pages for some examples of how to construct single and two brick forges:

http://ForgeGallery.EllisCustomKnifeworks.com

How can I cut the soft firebricks?

The soft insulating firebricks are very soft.  You can cut them using a hacksaw blade easily.  They can also be drilled with a metal cutting drill bit or even a wood boring bit!

Are soft firebricks resistant to flux?

No, soft insulating firebricks are not flux resistant.  If you are going to use soft firebricks in a forge that you intend to do forge welding in you will need to use other measures to ensure protection against damage from flux.  We carry a couple of different solutions to this problem:  Hard firebricks, Bubble Alumina, Mizzou.



Hard Firebrick questions

Are the hard firebricks flux resistant?

Yes, they are to a certain degree.  They work well in the bottom of horizontal forges to add some flux protection, however, they should be viewed as a consumable item in that they will eventually need to be replaced. 

How can I cut the hard firebricks?

A masonry blade in a chop saw will work.



Sairbond questions

How do I mix sairbond for use?

Sairbond is a high strength air setting mortar for laying fire brick.

FOR TROWELED JOINTS: The water required is up to 2 ½ gallons (U.S.) (9.5
liters) of water per 100 lbs (45.4 kgs) of dry mortar.

FOR DIPPED JOINTS: Add approximately 3 ½ gallons (U.S.) (13.2 liters) of water
per 100 lbs (45.4 Kgs). Too much water will reduce mortar strength.

Thin brick joints give best results. Each joint should be completely filled with mortar.



Insboard questions


How can I cut the Insboard to size?

You can use a hack saw, jig saw or a table saw, Insboard will cut easily.


Is this the material that is used to line the NC Tool forges?

Yes, it is, but the Insboard we carry is a better grade and higher density than that which comes in the stock NC Tool forges.  We can easily beat their prices for a forge relining kit, just send an email with the forge model and inside dimensions and we can cut your lining to size.  For the floor, they use a kiln shelf over top of ceramic fiber board.  We can supply you with hard firebricks as a replacement, or for even better flux protection, you can pour the hard part of the floor with Mizzou castable refractory.  Email us for pricing, we will have the lowest prices.


How do you ship full sheets of Insboard?

We build a crate to protect full sheets of Insboard during shipping. 

The Insboard is placed on a piece of plywood:

 

and then a frame is built around the Insboard pieces:

 

next, another sheet of plywood is sandwiched on top of the Insboard frame:

 
Finally, the assembly is screwed together:

 

This provides adequate protection for 24" x 48" sheets of Insboard, and is convenient for shipping up to about 4 sheets at a time.  For case quantities of Insboard (12 full sheets), we can palletize the case and ship it via a freight carrier, which generally results in a reduced shipping cost compared to Fedex or UPS.  Email us for shipping rates for case quantities of Insboard.


ITC-100 questions

How do I mix and apply ITC-100?

For ITC-100, the manufacturer recommends to mix it 2:1, so if you have a pint, mix it with a half pint of water.  My experience, indicates that mixing it a little thinner is just as good if you are using Satanite as a basecoat first.  Since you're using the Satanite as a protective coating, the ITC-100 doesn't need to serve this function.  Mix it thin, and apply the coats evenly.  Applying several thin coats is better than applying a single thick coat.  You'll likely have some left over for future patching.  Apply the ITC-100 over the Satanite only after the Satanite is fully cured.  You can use ITC-100 alone without first applying Satanite, you will just need to use more of this material.


I purchased my ITC-100 a while ago and haven't used it yet.  It is starting to dry out, is this a problem?

While most refractory materials come in dry form, ITC-100 comes partially pre-mixed in a clay consistency.  If your ITC-100 is starting to dry out you can store it in an air tight container if you like.  Just add water to get it back to its original consistency.


How much area will ITC-100 cover in a forge?

ITC-100 will cover 6 to 12 square feet per pint, or 3 to 6 square feet per half pint.  If you apply a basecoat of Satanite to your forge first, you can get by with the larger number for square feet coverage.  An additional benefit to doing this with Satanite first, is that Satanite is cheap and by building up a 1/4" layer of Satanite over you Inswool liner before applying the ITC-100 your forge will be more robust.


ITC-213 questions


What is ITC-213 used for?

ITC-213 is made to protect metals and graphite, including those exposed to molten metals. It helps to prevent steel and stainless steel parts from erosion, oxidation and fatigue from prolonged use. It can also be used to protect forge burner nozzels, pipe crucibles and electric heating elements.

How do I mix the ITC-213?

You mix it 3:1 with water, thus, if you have a pint of ITC-213, you would add 1/3 pint of water.

How much surface area will ITC-213 cover?

A pint of ITC-213 will cover 18 to 30 square feet.  A half pint will cover 9 to 15 square feet.


Nelsonite questions


As with any stabilizing compound, vacuum stabilizing is the preferred method to treat your handle material. This can be as simple as a brake system bleeder pump (available at auto parts stores for about $28) and a mason jar, or as complex as a motorized vacuum pump and a pressure/vacuum vessel. Having said that, the manufacturer just recommends soaking wood in the solution for penetration...and while that's not what we do, it is the way pool cue manufacturers use this stabilizer. Use the soaking only method at your own risk! It's easy to build a very simple hand pump vacuum stabilizer for small batches and in the near future we'll put up a short tutorial on how to do so. In the mean time, here's a good link to a simple system, just replace the medical vacuum pump with a hand pump:

http://www.knifeart.com/thevbycurmwi.html

and

http://www.knifeart.com/awbycurwil.html


Can I just soak my handle material in the Nelsonite?

Yes, and many people have good success doing just this.  You'll have to test out your material to see if the penetration is good enough, but I know plenty of people who just give it a long soak.  If you want to ensure there is full penetration every time, vacuum stabilization is the way to go, but if you're careful to test, you can just soak for some handle materials.



Castable Refractory Questions


How many cubic feet of material is there in the 55 pound and 20 pound bags of castable refractory you sell?

The amount can be found by dividing the amout of material in pounds by the density of the material in pounds per cubic feet.  This will give you the amount of material in a bag in units of cubic feet.  To find the amount in cubic inches, just multiply a factor of 1728 cubic inches/cubic foot.


Material

Density (pounds/cubic foot)

Amount (pounds)

Amount in Cubic Feet

Amount in Cubic Inches


Kastolite 26 LI

86

55

0.6395

1105.11

 

86

20

0.2326

401.86

Kastolite 30 LI

90

55

0.6111

1056.0

 

90

20

0.2222

384.0

Mizzou

141

55

0.3901

674.04

 

141

20

0.1418

245.11








Mizzou Questions

Below I've added the manufacturers instructions for Mizzou.  They are quite involved for the dryout cycle.  In practice, for applications in homemade forges, where you are pouring a shell of a limited thickness (typically 2" - 4"), most people just let it air dry for a from a few days to a week at room temperature and then bring the forge up to temp very slowly by intermittently running the burner for longer and longer periods of time until you bring the forge up to full temperature...you want to do this as slowly as possible.  If you are just pouring a hard floor in your forge over top of Inswool, you can be a bit more flexible in your dry times.  The key is to let the Mizzou dry slowly.

Mixing & Using Instructions
MIZZOU CASTABLE

--------- GENERAL INSTRUCTIONS --------
Material should be stored in a dry place.  Porous back-up materials or wood forms should be waterproofed. Absorption of water can result in reduced flow for the product. Forms must be stout and water tight. This product is designed to be mixed with water and then poured/handcast into place.  For best results, water should be maintained at 50-70F.

--------- MIXING REQUIREMENTS ---------
Approximate Water For Installation: 55 lbs. to 5 pints of water.

Mix for at least three minutes. For best results, wet mix temperature should be maintained at 60-75F. Minor adjustments to the amount of water are permissible to achieve desired flow. Do not exceed 11.0% water under any circumstances.

--------- INSTALLATION ---------
Place material promptly. Do not trowel to slick finish. At temperatures above 60F, air cure, keeping surfaces damp and/or covered, for 16-24 hours typically or until a hard set has developed. Lower temperatures will increase the time before a hard set develops. The best results are achieved at curing temperatures of 90-110F. Keep material from freezing during air cure and preferably until a dryout can be initiated. Freezing of this product prior to water removal can cause structural damage.

-------- HEAT UP SCHEDULE --------
Never enclose a castable in a vapor-tight encasement as a dangerous steam explosion may result.

Typical dryout schedule for a single layer, 9"  thick or less:
ambient to 250F at 75F per hour
hold at 250F 1/2 hour per inch thickness
250F to 500F at 75F per hour
hold at 500F  1/2 hour per inch thickness
500F to 1000F at 75F per hour
hold at 1000F 1/2 hour per inch thickness
1000F to use temperature 75F per hour

 

Kast-O-Lite 30 LI

--------- GENERAL INSTRUCTIONS --------

Material should be stored in a dry place. For best results, material should be maintained at 50-70F prior to casting.

Porous back-up materials or wood forms should be waterproofed. Absorption of water can result in reduced flow. Forms must be stout and water tight.  Kast-O-Lite 30 LI is designed to be mixed with water and then poured/handcast into place.

Add only clean water suitable for drinking.  For best results, water should be maintained at 50-70F.

--------- MIXING REQUIREMENTS ---------

Approximate Water For Installation = 8.6 pints per 50 pounds of material.

Mix for at least three minutes. For best results, wet mix temperature should be maintained at 60-75F. Minor adjustments to the amount of water are permissible to achieve desired flow.

--------- INSTALLATION ---------

Place material promptly. Do not trowel to slick finish. At temperatures above 60F, air cure, keeping surfaces damp and/or covered, for 16-24 hours typically or until a hard set has developed. Lower temperatures will increase the time before a hard set develops. The best results are achieved at curing temperatures of 90-110F. Keep material from freezing during air cure and preferably until a dryout can be initiated. Freezing of this product prior to water removal can cause structural damage.

-------- HEAT UP SCHEDULE --------

Never enclose a castable in a vapor-tight encasement as a dangerous steam explosion may result. Typical dryout schedule for a single layer, 9" (229 mm) thick or less:

ambient to 250F (120C) 100F (55C) per hour

hold at 250F (120C) 1/2 hour per inch thickness

250F to 500F (120C to 260C) 100F (55C) per hour

hold at 500F (260C) 1/2 hour per inch thickness

500F (260C) to use temperature 100F (55C) per hour





Ceramic Platen Liner questions


What does a platen liner do?

The ceramix platen liners are made to be epoxied onto the metal platen that comes on most belt grinder. The material has a low coefficient of friction and is very flat.  This often reduces the heating effect of the belts in use as well as helps to minimize "belt bump" while using finer grit belts.  The flatness of them aids in doing flat grinds and the raised edges help improve defined plung cuts.

Does the ceramic platen liner arrive ready to glue on?

Yes, the platen liners arrive ready to be glued on to your metal platens.  You should, however, ensure that your metal platen is flat and free of any dips or grooves.  You can do this by taking it off of your grinder and sanding it on a flat plate by hand.  It's good to do this to ensure you are gluing the ceramic platen liner to a flat surface so you don't create any undue stress on it.

How do I glue it onto my platen?

I always recommend JB Weld.  JB Weld has a high temperature rating than most other epoxies on the market and has proven to be very effective.  If you use a lesser epoxy, it may be prudent to build a small "lip" at the bottom of the platen liner that will "catch" it if your epoxy should let loose. 

Are the leading and trailing edges chamfered to prevent cutting or wearing the belt?

No, they do not arrive chamfered from us, this is something the user will need to do if they want.  You can do this by roughing the radius in with a coarse grit belt (1.e., 80 - 120 grit), and then cleaning it up with a fine grit belt (i.e., 220 - 400 grit), or until you are satisfied with the smoothness of the transition region. I prefer to use the slack belt region of my grinder to do this operation.  In addition, some people choose to radius the edges or parts of the edges to assist in attaining different plunge cut geometries. For instance, I have known people to leave the upper half with sharp edges, and radius the lower half edges.  This way you can have a sharply defined plunge cut by using the upper portion of the platen liner, and if you desire a more sweeping plunge, you can use the lower half.  It is up to the user to determine if this is something they want to be able to do or not.

How long will the platen liners last?

As with most things we deal with, the ceramic platen liners should be viewed as consummable items.  They only cost as much as two or three good grinding belts.  The lifetime you will experience with your ceramic platen liner is dependent on several factors, such as the frequency with which you grind, whether or not you use your platen to profile on (not a good idea), etc.  They will eventually wear if you tend to grind in the same position all of the time.  I've been using the same one now for almost 4 years, and it's still holding up well.  If you are a production grinder, turning out 100 blades a week, you'll get less lifetime.  In any case, the added benefit of using one is wortth the cost of replacement for most people. 

When my platen wears out, how do I remove it?

Most epoxies will soften with added heat.  Try the kitchen oven or a blow torch to assist in removal.


Wire Rope questions


Info coming soon!


Venturi burner questions


How hard is the kit to put together?

It's not too bad.  If you have access to a drill press, drill index, hack saw, crescent wrench, pipe wrench, and a 1/4-28 tap you can do the job.  If you have access to a lathe, even better, it will make several of the steps easier.  I make available an 18 page step-by-step instruction booklet with images showing each step with the burner kits, just shoot me an email requesting this document after placing your order for the burner kit.

How large of a forge will the burner heat up to forge welding temperatures?

This a somewhat difficult question to answer without seeing the particular forge you plan to build.  If we assume a Inswool lined forge, topcoated with Satanite, and maybe some itc-100, a good estimate would be 350 cubic inches per burner.  Thus, if your forge has a toal volume of 700 cubic inches, you would want to go with two Venturi burners.  If you're just building a forge for forging in and heat treating (austenitizing) in, you can go with a larger volume. 


Forced Air Burner questions


Are your Forced Air Burners plug-n-play?

The kits require the user to put them together, however, the Assembles Forced Air Burner comes painted and ready to use once the user couples their blower to the burner and attaches a regulator to it




Propane Regulator questions


Info coming soon!


POL fitting questions


Info coming soon!


Needle Valve questions


Info coming soon!


Forge questions


Info coming soon!


Etcher questions


Info coming soon!


Hydraulic Press questions


Info coming soon!


InsTuff questions

Manufacturer's information directly from the bottle:

Handling Instructions
- After air drying, Rigidizer provides a harder and resistant, but less resilient, surface on the material being treated.
- Container should be tightly sealed upon completion of job.
- Avoid freezing, but if it occurs, Rigidizer should be thawed thoroughly and remixed.
- One gallon will cover an area approximately 50 sq. ft. with one brush coat.

  

Directions for Applying
- Remove dirt, grease, and oil from area to be coated.  For best results, surface should be rough or porous.
- Stir Rigidizer thoroughly before use.
- Allow Rigidizer to air dry at room temperature.  If desired, drying time for thin application may be shortened by using slightly higher temperatures up to 150 degrees F.
- On some surfaces, two coats may be required to obtain desired hardness.  Allow 4 hours between coats unless heat is applied to speed drying.
- Rinse equipment thoroughly in water as soon as possible after application is complete.





Ball Valve questions

Are your ball valves the same as the ones available at the local hardware store?

Likely not.  Our ball valves are rated for gas service use, while the ones available at the local hardware stores are typically liquid (water) use only.


Gate Valve questions


Info coming soon!


MIG Tip questions


Info coming soon!


Sch. 80 Pipe Nipple questions


What size tap do I need to use to install a standard MIG tip orifice into the nipple?

A 1/4-28 tap should do the job.



Ward T questions



Info coming soon!


Wrought Iron questions


Info coming soon!


 Heat Treating Salts questions

How do I rectify my High Temp Salts?

Carbon rod rectification will remove the dissolved nickel and chromium oxides, you'll need to scrape them off as they are deposited on the rod.  You do this by inserting the carbon rod into the salt when it is up to operating temp and stirring gently.  Be sure to wear all of your protective gear when you do this.  Since most people don't have a good means of checking the chemistry of the salt bath, I prefer to just rectify via turnover, that is, I'll change out 5 - 10% of the salt once I start to notice a significant amount of decarb from the other oxides formed in the bath.  It's a good idea when you first set up your salt bath to make a reference coupon so you have a gauge for comparison.  To do this, get some high carbon shim stock or feeler gauges.  Make sure they all have the same surface finish on them.  Dip one in the salt and soak for a preset time (5 minutes or so).  Once you remove it, wash it off well and dry it.  Use this one as the reference for future tests.  That is, after your salt bath has been in operation for a while and you think you are starting to see more decarb present, you can run another coupon through the bath for the same time frame and after washing and drying it compare the surface finish.  Any decarb and indication that the sale bath needs to be rectified will be obvious if you've taken the time when you first set up your salt pot with a reference coupon.

The one nice thing about the barium free salts that we carry is that you aren't forming barium oxides.  With natural drag out losses in the salt, you'll find you don't have to do a turnover very often....and the high temp salt is fairly cheap, so it's not too big of an issue.  If we were running large salt baths in a continuous process line, it would make more sense to check bath chemistry and rectify accordingly, but since we're so small volume (at least I'm assuming you're doing reasonably small volumes like me!), it just doesn't make sense to spend the extra money on analysis costs.

If you feel that you must add something to the salt bath rather than rectifying through turnover, there are three methods you can use.  One is to add boric acid to the salt bath and mix it in. (recommendations from references is 125 gm per 100 kg of salt).  The other method is the addition of ammonium chloride to the salt bath to achieve neutrality.  Finally, methyl Chloride gas can be bubbled through the salt bath for rectification purposes, but most small users will not have this capability.  Personally, for small salt baths, I'll just stick to turnover, it's easy, safer, and I don't have to pay a chemist to analyze my salt bath so I get my rectification ratios correct.  With a reference coupon I can tell pretty easily when this needs to be performed.


When I wash my parts off do I have to worry about how to dispose of the residue?

No, not if you are using Barium free salts such as the ones we sell.  The residue you wash off will contain simple ions of sodium, potassium, chloride, etc.

Where can I find a carbon rod?

Search for carbon/graphite EDM rods.  You can find them in sizes from 1/8" (too small) up to as large as 12" diameter (way too big!)  I prefer something in the range of 3/4" to 1" for a small salt bath.


High Temperature Tools & Refractory