How to Mix a Weight/Volume Paraloid B-72 Solution

What is Paraloid B-72?

Paraloid B-72 (formerly called Acryloid B-72) is a stable clear acrylic resin used in conservation as a coating, consolidant, and adhesive. B-72 is an ethyl-methacrylate copolymer soluble in acetone, toluene, xylene, and ethanol. Since most historic wood coatings are insoluble in aromatic hydrocarbons, B-72 has proved to be a safe barrier coat and surface consolidant on the majority antique furniture surfaces. Also, since the resin is not soluble in aliphatic hydrocarbons, paste waxing over the surface is still a viable maintenance procedure. Paraloid B-72’s thermoplasticity, solubility parameters, and durability are the primary reasons that it has found extensive use in conservation treatments.

Supplied Forms

B-72 can be purchased either already mixed in solution or in clear, odorless pellet form ready to dissolve in a custom solvent blend and concentration.  I have found the latter method easy enough for my practice. Requiring no more than a few minutes and a few simple tools, one can easily mix their own B-72 solution. The following is how I go about the task.

The Tools

Digital scale with 0.1 g resolution.

Small glass jar with lid

Cheese cloth

Cotton/ hemp string

Small funnel

Permanent Marker

Measuring cup measuring ml

Tap water

Desired solvent(s)

Paraloid B-72 pellets

Mixing it Up

Because we will be making a weight/volume solution, the first task is to decide the final desired volume. For this run I have decided I want only 100 ml of final solution. Using your measuring cup, measure out 100 ml of tap water and transfer it to the clean glass jar.

Mark the volume with a permanent marker on the side of the jar. You may discard the water and towel dry the jar. You now have a mark on your jar displaying your final volume.

Setting the jar aside, take your digital scale and weigh out your pellets in grams. To figure the concentration percentage of the solution, you only need to know the grams per 100 ml. If you want a 20% solution, you will use 20 grams pellets for the final solution of 100 ml. Note that I did not say “per 100 ml of solvent”. Weight/volume solutions are figured by adding solids first and then “topping up” with solvent to your desired final volume.

Once you have your 20 g (for the 20% solution), take a small square of cheesecloth and tie the pellets into a bundle with the string. You do not want to use synthetic string for this as it may end up dissolving depending on your solvent blend. Make sure to leave at least 6” of string for a handle for the pouch. Drop the pellet bundle into your glass jar with the string hanging out.

Now, using your funnel, “top up” with solvent to the permanent marker line at 100 ml. Pull the string up and screw the lid on a best as you can to allow the bundle to suspend in the solvent. 

Check every hour or two. Dissolution time obviously varies greatly depending on amount of resin and the solvent choice. When the B-72 is completely dissolved, you can pull out the cheesecloth and discard. You now have your 20% Paraloid B-72 solution. Simple as that. No mess, no fuss.

The Solution Dilution Solution

Ah, but wait… What if I want to try different concentrations for my project? The solution for your solution dilution is found in Pearson’s Square. Pearson’s square is a formula used to change concentrations of solutions. It is as follows:

A Stock Solution (%)

B New Desired Solution (%)

C Diluent (%)

X Part of Stock needed for New

Y Part of Diluent needed for New

X = B – C

Y = A – B

X + Y = D

So, for example, say I took my 20% solution and wanted to make a 5% solution out of it. In order to determine how much more solvent to add (diluent), I plug my numbers in the formula…

A Stock Solution (%) = 20

B New Desired Solution (%) = 5

C Diluent (%) = 0 (There are no solids at all)

X Part of Stock needed for New

Y Part of Diluent needed for New

Parts of stock solution needed:  5–0=5

Parts of Diluent Needed:  20-5=15

So, 5 Parts stock solution to 15 parts diluent = My 5% desired solution.

I hope this helps anyone who has wanted to try B-72. This method can be used for any resin. I found it is much preferred to allowing the resin to clump in the bottom and have to periodically stir it up. This cheesecloth method really is very hands off. Any questions? Leave a comment and I’ll get back to you.

RESOURCES

Paraloid B-72 pellets.  Available from Talas 330 Morgan Ave Brooklyn, NY 11211  212-219-0770 http://talasonline.com/

The Cameo Database – “Paraloid B-72” http://cameo.mfa.org/materials/record.asp?key=2170&subkey=6848&Search=Search&MaterialName=paraloid+b72&submit.x=0&submit.y=0

Astounding Wood Identification Technology!

One of the cooler things I've seen recently...

Make Gift-Giving Meaningful

Stage Two: Excavation Complete

Stage two of the studio construction is completed! This past Saturday my neighbor Jeff came over to do the site work. Both he and his partner were expert with the excavator. I couldn’t help but notice how the bucket seemed like an extension of their arms. It was really impressive.



They first tackled the driveway, making quick work of it. Then they tore up the grass and topsoil where the building will be done. They brought in quite a bit of fine gravel and leveled it out really nice. I also had them pull up some of the red pine stumps we cut a few weeks ago. Then we put in a two car parking lot near the road and continued the driveway down the front of the building spot. This will be nice to have vehicles back up for loading and unloading situations.





It goes without saying that Eden thought the whole thing was a riot. He loved the excavator and all the ruckus it made.



Site work complete!



View from where the bench window will be.

Thank you again to all of you who contributed to the fundraising campaign to get this project launched. It really means so much to my family to have your support.

This is the last step we will be accomplishing before snowfall. To be continued on the other side of winter. For now, it's time to hibernate...

Building a Studio: Stage One Complete!

So it has officially begun. The studio building project is under way. A couple Saturday mornings ago I had my arborist brother-in-law, Mike, and two of his buddies to come over to take down a few trees. We took down a hand full of red pines and poplars.



Mike did a great job teaching me how to fell a tree with a chainsaw. I was only used to (and comfortable with) taking down small trees with an axe. Big macho scary chainsaws are a bit much for my taste. But I did it. And I still have all my appendages.







We were able to get a good little collection of red pine logs we’re going to mill up. I will hopefully be able to get boards for part of the inside of the studio.





Monday morning Mike came back with chipper in tow. He and I spent only an hour and a half sending the downed trees through. Intimidating machine, for sure. Julia and Eden watched on from a distance, Eden administering the events with hoots and hollers.



So make a check on stage one. We’ve cleared the way for my neighbor, Jeff, to come to do the site work. It’s scheduled for about two weeks from now.

The Birth of a Tool

A dear friend sent me this link recently. Beautiful cinematography, Bon Iver soundtrack, and old world Latvian blacksmiths? What's not to love about that?

The Birth Of A Tool. Part I. Axe Making (by John Neeman) from John Neeman Tools on Vimeo.

Holdfasts Blacksmith Style

For my birthday, my dear wife let me commission a local blacksmith to make me a pair of holdfasts. After finding the right man, I got together some specs on what I wanted. I found out that the Koontz holdfasts were made from 11/16” cold rolled steel for 3/4” bench holes. This is what I was after.





I also decided that I wanted a shepherd’s hook style (like the later Koontz variety) rather than the low profile version. Boy, do these puppies hold securely! They are really easy to set, hold like the dickens, and are really easy to release. Check it out:





I had Jerry Gallant from Kenduskeg, Maine make them for me. He has an excellent 18th century style blacksmith shop that he works out of. His specialty is making reproduction cannons. Here is a video tour of his shop:



And here are his cannons firing: http://www.youtube.com/watch?v=9gZdnwS7G-U&feature=channel&list=UL



Pretty impressive, I’d say. If you don’t know a blacksmith in your area but want blacksmith made holdfasts, you can give Jerry at call at (207) 659-0118.

Making a Simple Try Square

I find that I often get time between glue-ups and finish coating to plink away at small little projects. I made a simple little try square out of cherry this week. It will be great for my reenacting at Leonard’s Mills next summer. This one is a 12” square. I also have a 6” in the works. It was a fun project. I just sort of made it up as I went along.



Straight grain cherry stock





Squaring the stock with handplanes



Used Dozuki saw to cut the bridle joint for the blade to fit into



Chopped out the waste with 1/8” chisel


Hot Hide Glue for glue up



Clamped my 6” Starret into the square to ensure it won’t slip



Drilled out two holes for the pins. I used a modern twist bit but then slightly angled the bit once through. This gave the hole a subtle ovality resembling antique drill bits. Then I shaped the cherry pins with a bench chisel.



Hot hide glue installation of pin



Everything trimmed flush. Make sure to check for square on all sides!



Marking out details



The coping saw makes quick work of this



Files to smooth out saw marks


Three applications of dewaxed bleached shellac applied by rag. Then scuff sanded with maroon synthetic steel wool and waxed with Antiquax in Liberon #0000 Steel Wool.



Complete!








Ps. A few things I wish I had done:

1. Left the blade about 1/4" proud of the top of the handle. This makes truing up easier later. In fact, I may trim the handle down a bit so that I can have at least an 1/8" for later if it goes wonky on me.

2. Saw the bridle joint from both sides of the handle. This would make a cleaner looking joint. (Refer to Bob's video above for an explanation.)