After a long brew day, and a series of mishaps on a small batch (2 gal), it became clear to me that I needed better volume measurement in-kettle, rather than just between transfers. Currently, I use fermenter buckets to hold sparged wort from my mash. As I use a hybrid BIAB method where I still fly sparge from an HLT (Hot Liquor Tank), the buckets are a great transfer vehicle and are also marked with volumes. In a 5 gallon batch, I know I need 6.5 gallons to boil down to 5.5ish in one hour. With nearly 1/3 dead space in my kettle, I end up with 5 gallons, plus a small amount extra to make up for the dead space occupied by trub in the fermenter.
But with a small batch, gauging volumes by eye that you don’t use regularly can quickly turn into a nightmare. Also, depending on the outside temperature and humidity, I’ve noticed changes in my boil-off volumes. So, in the name of accuracy, I decided it was time to acid etch my kettle.
This is a fairly simple process and won’t harm the stainless steel. It just removes a small layer of metal, which then reflects light differently to show the etchings.
The list of tools you’ll need.
- your kettle (cleaned)
- 1 exacto knife
- 1 roll electrical tape
- 1 set of 1/2 inch letter/number stickers (mailbox letter sets work)
- 1 pencil
- 1 hair dryer
- 1 five gallon bucket with existing measurements
- 9V battery
- speaker wire
- wine vinegar (red or white)
- table salt
- You must first decide where you want your etched marks – I chose directly opposite of the ball valve, as that’s where I’ll be looking when the kettle is on my stove. Using electrical tape, put a marker (piece of electrical tape) as your center line for your markers on the rim of the kettle. This marker will be used later and also act as a guide for where to place gallon markers inside the kettle.
- Fill the fermenter bucket with 5 gallons of water using the measured mark on its side.
- Dump the water into your kettle.
- Once the water settles and is still, put a marker for 5 gallon the volume right above the water line.
- Put the fermenter bucket below kettle and drain 1 gallon from the kettle to the bucket using the ball valve and tubing on your kettle. Note: If you don’t have a ball valve bucket, just use a quart measuring cup to remove the gallon. You’ll have to wait for the water to be still again before marking.
- Mark the next volume inside your kettle.
- Repeat steps 5 & 6, continuing down to the 1 gallon marker.
- Empty the last gallon of water to your bucket and dry the kettle. Use a blow dryer to get the area which you’ll be etching, bone dry.
- Using a straight edge ruler or similar object, draw a line with your pencil from the center-line marker down to the bottom of your kettle. Make sure it’s straight! It may be difficult to see with just one pass, so you may need to make multiple passes holding the pencil at different angles.
- Using a sheet of paper or piece of a box, make a pencil mark perpendicular to the center line along the gallon markers inside your kettle.
- You can also gauge your half-gallon markers by eyeballing the halfway point between gallon markers, or measuring the halfway point with a measuring tape. If you have enough space between gallon markers you can also use tape to mark them in steps 5 & 6.
- Remove your tape markers. You should end up with something like this:
- Now you can begin placing the stencils from your 1/2 inch number sheets. Using the exacto knife cut around the numbers, carving out a 1/4-1/8 inch of the sticker material around the number. Some number/letter packages are packed together tightly and you may need to cut into the neighboring letters and numbers, to make the needed space around the numbers we’ll need for this project.
- For the markers on the side of each number you can use the zero or ‘O’. Just make sure you have enough. For 8 gallon markers you need 16 zeros or O’s.
- For the half markers you can use two ‘T’ letters to make a box. Our use electrical tape and cut a rectangle out.
- Once you’ve completed the stencil placement you should have something like this:
- Now you can begin etching. Connect your battery to your kettle and Q-tip using the speaker wire. Strip about 1 inch from each end of the wire and connect to the battery and kettle. Wrap the stripped wire around the cotton part of the Q-tip. IMPORTANT: connect the NEGATIVE side of the battery to the Q-tip. Connect the POSITIVE side to the kettle. This ensures the flow of electrons is removing metal and not adding metal from the wire.
- Mix 1/4 cup of vinegar with 1/4-1/3 tsp of salt.
- Dip the Q-tip into the mixture, making sure the wire is touching wet Q-tip. I recommend rubbing the excess liquid off on the inside of the cup.
- Rub the Q-tip on exposed kettle inside the first stencil. Be sure to rub evenly and slowly across all the exposed metal. It only takes about 10-15 seconds to etch a piece. You should sees small bubbles around the Q-tip and may hear quiet sizzling.
- Re-wet the Q-tip for each stencil and follow the same process. You should be able to see that the metal inside the stencil is lighter and brighter than the rest of the kettle. By the third stencil you should notice the Q-tip turning brown. That’s good and nothing to worry about. You can use the same Q-tip for the whole process. When you’ve etched all the stencil, remove the tape.
Signs you’re doing it wrong:
- The wire on the Q-tip is turning white or the Q-tip is turning green. You have the positive and negative connections switched.
- The stencils are peeling off. You’re rubbing too hard or your Q-tip is too wet.
- Nothing is happening (no bubbles, no color charge, and no shiny kettle parts). Double check your connections. Your battery may also be dead.
The preparation for this processes is the most tedious part, because you want to make sure everything is accurately marked and as straight as possible, but the end results are great. I am quite happy with my results and look forward to having the added assurance that my volumes are accurate inside my kettle as well as being able to watch my boil off volumes.
Merlin U Ward