Thursday 16 August 2018

Screws.
I thought it would be useful to give some information about the basic raw material of the army, the woodscrew.
The original magazine article that inspired me suggested the use of quarter inch screws for infantry and three eights inch screws as cavalry. I will discuss how I build cavalry in a later article. As far as foot soldiers are concerned I decided to use a larger screw and settled on half inch number 6 slotted screws. In those days    ( late 60s and early 70s)  these screws were readily available  in a self coloured finish, that is to say in raw steel. However more recently the use and therefore the availability of slotted screws has seriously declined. Slotted screws are really essential,  in my opinion, as they have a flat space between the thread and head called a shank, This area is used for applying the rank markings. Modern cross headed screws do not have this feature as the thread goes right to the head.
 In addition even when slotted screws can still be found they have a finish called BZP meaning bright zinc plated. This is to provide an element of rust proofing to the screw. Personally I have always found that the paint I use not only covers any surface rust but fully protects the screw in the long term. The BZP finish is a problem however in that it is very hard if not impossible to get the paint to adhere adequately. After a struggle with this problem I sought an answer on the inter web. I found it on an American site. In essence this site referred to treating modern metal furniture hardware to give it an antique finish. The solution is to soak the BZP screws in pickling vinegar !!!!!!! yes another crazy idea !!!! However after a bit of experimentation I made it work very satisfactorily.
 In essence the screws are soaked in pure white pickling vinegar for at least an hour, 90 minutes is better. Ordinary vinegar is not strong enough for the job. I usually soak batches of 400 or so at a time in an old ice cream  tub. The BZP coating just vanishes leaving the screws in a self coloured (raw steel) condition which is perfect for painting. I find that after two batches the vinegar needs changing. By the way, the vinegar does give off a bit of a wiff so consider where you perform this activity. I am fortunate to have a workshop but a shed would work well. After soaking,  the screws are emptied into a sieve and washed in water thoroughly. My wife refused to let me use the kitchen sink for this part of the process (cant imagine why not)  so I have to use  a hose outside over a drain. The trick then is to quickly dry the screws to minimise flash rusting. I do this by laying the washed screws on a double thickness of old towel and then spreading them out evenly and heating with a hot air gun. Don't forget , if trying this, that the screws will get real hot !!!! After cooling a bit I just box the screws up for future use. I find only a little surface rusting occurs provided they are stored indoors and anyway a little rust actually gives a better painting surface.
It is still possible to buy BZP slotted screws although you do have to search the inter web. To find self coloured screws is nowadays unlikely unless you are very very lucky indeed. I managed to buy 20,000 very old stock screws a couple of years ago via a contact in the trade but that was a fluke. These screws are still made but only in India and China and I hate to think how many you would have to buy to actually get an order accepted. If anyone reading this ever finds a source of supply please let me know !!! In the meantime if you want to try using screws as soldiers you will have to use BZP screws and get them where you can. If anyone tries out modern cross head screws, which will still need treating to get rid of the BZP,  I would very much like to know how you get on with painting.

No comments:

Post a Comment