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Antique Safes/Replacing Plaster Core.


QUESTION: Dear Andy,

My safe is a circa 1890 Halls Safe and Lock Co. Floor Safe. Dimensions are 27 1/2"H x 17 1/2"W x 17 1/2"D. Currently, my restoration project is under way: disassembled, parts are being machined/cleaned/repaired/plated etc. as we speak.

However, in order to access the combination dial and bolt mechanism etc. I had to remove the inside door plate/panel and remove the plaster (?) filling in the safe door. When the door is reassembled, what modern product would you recommend for replacing the removed plaster? Something that wouldn't introduce expansion or moisture problems.

As always, I look forward to your learned reply.


ANSWER: Hi Darin,

Generally I don't recommend removing the insulation media as you can run into a plethora of problems.   (I like the "Three Amigo's" reference!)

In order to keep the insulation material out of the lock and bolt work areas, the safe originally had a "dam" installed.   Hopefully you were able to recover it with little damage, as you WILL need it to replace the insulation material.

Second major problem, when mortar, concrete, plaster of Paris dries it tends to expand.   This is one of the reasons that expansion joints are placed in driveways and sidewalks.    Depending on the material that you use, you can count on anywhere from a 1% to 3% expansion.   Some concretes will shrink due to loss of volume as it cures.  This can result in cracking and further loss of material later.    Plaster of Paris has a very low expansion rate of about 0.1% and it is not water soluble after it dries.   Plaster of Paris is very good at resisting heat transference.

Note:   It really doesn't matter WHAT material you use as this container does not meet ANY current standards for heat or fire protection.    While you may do a really good job on the door, you haven't done ANY repair work to the other five sides of the safe.    As potential cracks and broken insulation in the safe walls provide means of ingress for heat - this safe should NOT be used for overnight storage of any items which may need protection from a fire.

So obviously the problems that will occur WILL depend on the material that you will be using.   Bottom line you basically only get one chance at pouring and not having a problem.    The biggest problems don't occur with the actual material, but with the consequences of its actions.   If swelling of the door frame, casting occurs, the door will no longer fit the door jamb.    Grinding of the cast material is NOT the answer.    The door frame material must be blocked in place before pouring any insulation material.   Use necessary framing to clamp the cast iron walls of the door, to hold them in place so that NO swelling of the door frame will take place.

I recommend pouring the material with the door laying on its face.    All exposed areas inside the door should be properly cleaned and preserved with a rust prohibitive paint as any moisture in the insulation will begin to rust these areas.    Similarly the dam must be repaired and painted with rust preventive to protect this area.    It also needs to be sealed around the lower edges so that insulation mix will not flow into the bolt work area.    You will not be able to re-clean these areas afterwards.

Oh, yeah don't forget to clean and lubricate the bolt work areas AND to reinstall them before installing the dam and pouring the insulation.   Forgetting could be a critical error!  :(

Hope this answers your question and/or at least gives you some food for thought.   Bottom line it doesn't matter what you use, as long as you take out all of the variables from the equation AND take appropriate steps to protect the door and other components.

---------- FOLLOW-UP ----------


As always an exceptionally comprehensive answer. THANKS! (And on a holiday none the less)

First just FYI I did salvage the dam material (whew!).

Second, thanks for the reminder about the other five sides. Very good point.  Turns out the safe itself will most likely be the most valuable thing. Its more a passion for the safe than trusting it to protect anything.

Third, thanks for the advice to block the door frame material. I would have never thought about that. Plus the advice about properly painting / coating / lubricating everything.

Fourth and final, the bolt securing the nut for the latch was drilled on its tip/end and flared to prevent the nut from loosening.  Should I come back with the same technique or use a nylon nut to prevent loosening?


p.s. Steve Martin, Lorne Michaels and Randy Newman rock.

Hi Darin,

If you want to keep the handle cam nut original, then I wouldn't hesitate to use one of a number of techniques to secure it.

1.  Drill the nut and handle shaft at a 90 degree angle and insert a pin through both.

2.  Drill the nut and handle shaft - parallel to the handle shaft, at the thread area.   Tap the small hole and insert a set screw or screw to lock them together.

3.  Make an oversize washer with two to four wings.   When you have the handle cam nut secured with the right amount of torque so that the handle, cam and bolt work will operate freely, then fold up the wings around the nut, making them tight against the flat sides of the nut.    This washer needs to be of sufficient strength so that it won't break loose, but still malleable enough so that you can bend it.

4.  Peen the end of the handle shaft slightly so that the nut cannot back out on its own.   3 to 4 pricks with a pointed punch around the outer edge of the threaded portion of the shaft will deform just enough material to keep the nut from unthreading, yet still allow it to be removed at a later date.

5.  As per your suggestion, use a NYLOCK nut to lock it in position.    This assumes of course that there are sufficient threads to extend BEYOND the edge of the nut.   Many of these handles used a thinner nut with the threaded portion of the shaft cut down to match.   There may not be enough thread on the shaft to use a NYLOCK nut.

As usual think each step of your project through completely, contemplating following steps, so that everything works.

It's NOT a bad idea to actually work out a "production schedule sheet" for each step, in advance so that you know what you are currently working on and more importantly, what the next step is.     I do this on most of my machine shop projects to keep me on track.

I try to only do one major step at a time, that way if something doesn't work out, I only have to back up that one step.     If you perform many steps, it is much more difficult to detect WHERE the problem is and what would be the necessary corrections.    Obviously we learn from our mistakes more than our successes - hence the word of warning concerning bracing of the door frame!  LOL

Good luck on the project!  

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Terry V. Andreasen (Andy)


Safe and Vault related Questions; Antique Safe Repair and Restoration; With over 44 years in the Safe & Vault industry, if I can't answer your question I know where to get the answer. Current Project: Restoration of an Ely Norris Cannonball Safe from the early 1900's. Will answer Safe & Vault related questions concerning age, value, restoration, moving, opening & repairing, parts, operation and history. Note: It is not my intention to teach you to open safes or to provide information which may aid in the unlawful opening of a safe. I will not give out drill points or information which I deem inappropriate.


44 years in the Safe & Vault Industry. Owner and Service Manager for one of the largest Safe & Vault companies on the West Coast. Graduate of Lockmasters Safe Lock Servicing, Safe lock Manipulation and Safe Deposit Lock Courses. Graduate of Locksmith Institute. Author of "The Coffee Table Guide to Antique Safes". Certified Instructor for the California Locksmith Association teaching Basic and Advanced Lock Servicing, Basic Safe opening and Repairing. Factory Trained by AMSEC, LORD Safes, LeFebure, Mosler, KabaMas, LaGard and Sargent & Greenleaf

Safecrackers International and the National Antique Safe Association Safe & Vault Technicians Association

The Coffee Table Guide to Antique Safes

Graduate of Locksmith Institute 1972 Graduate Lockmasters Safe Lock Servicing 1974 Graduate Lockmasters Safe Lock Manipulation 1975 Graduate Lockmasters Safe Deposit Lock Servicing 1985 Instructor Certified - California Locksmith Association - 1985 Factory trained by AMSEC, MAJOR, STAR, Johnson-Pacific, Kaba-MAS, Allied-Gary, ISM, Lord, Brown Safe, EXL, Mosler, Diebold.

Awards and Honors
2009 - 2015 Listed in AllExperts top 50 Experts. All Experts Categories - Safes & Security Containers, Locksmithing, Antique Safes. Retired US Army Chief Warrant Officer (CW4), with 39 years of total service. With numerous awards from Vietnam, Desert Storm and Operation Iraqi Freedom. US Navy - 1971-1981 US Army Reserve 1984-2013 US Army Retired

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US Secret Service, FBI, BATF, Local Law enforcment agencies, Diebold, Hamilton Pacific, Red Hawk Int., Chubb International, Bank of America, Wells Fargo Bank, Mechanics Bank, El Dorado Savings Bank, many Credit unions and smaller banks. McDonalds, Togos, BurgerKing, TacoBell, Carls Jr. FoodMaxx, SaveMart, Lucky's, Albertson's, Raley's, Safeway, NobHill, Bell Markets, PW Markets. Great America, Century Theatres, Cinemark Theatres, UA Cinemas, and many homeowners and small businesses. Provide warranty service for lock and safe manufactures. Service area is Northern California - Fresno to Oregon, including western Nevada

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