Vintage Garden Syringe Sprayers    

Back Making cup washers

Various web sites give methods for making cup washers, but they involve making special tools. The method described here works using the syringe barrel and some washers as a mould . Using the technique describe you will get cup washers which are a better fit than those available commercially, but they may not be as compressed as some. This could mean that they may dry out more easily and also wear more quickly, however, the ones I have made have made over the last year are still working, and as they are relatively quick and cheap to make so replacing them will not be a problem.



Finding the right leather is one of the most difficult thing to do. The main supplier of leather on Ebay offers 1.5, 2.5 and 3 mm. thick pieces of leather (search for Veg Tan Leather off cuts). You will be moulding the leather so you need to make sure it is suitable for this purpose. As a rule of thumb, the thickness of the leather needs to be half of the difference between the inside barrel diameter and the metal washer diameter. For example a 15/16 inch (24 mm. ) barrel with a ¾ inch washer (19 mm) would require 2.5 mm thick leather. There is some leeway either side of this, and there is always the option to use larger or smaller size metal washer. The 2.5mm thick leather seems to be the most useful.  Apart from the leather the only other thing you need is a few metal washers of the same size as the metal washers used in the syringe.

Stage 1

Measure the internal diameter of the syringe barrel and the diameter of the plunger rod . Add 10-12 mm. to the internal diameter to get the size of the washer blank required. A 32 mm blank is fine for a 7/8 syringe barrel, but add a little more for larger barrel sizes. Using a punch or the cutting compass cut out two blanks. You can also use an ordinary pair of compasses to mark a circle and cut this out carefully using a craft knife, but I suggest you make the blank a fraction bigger if using this method. The cutting compass is easier to control on dry leather, but soak the leather for a few minutes before cutting it if you are using a punch. Cut a hole in the centre with a diameter 2 mm less than the plunger rod diameter. Using a punch is the best way of doing this, but you can drill the hole if you haven’t got punches.

Stage 2

Put the nut on the plunger rod, then add about 3 washers, the same diameter as the washer taken from the syringe. Slightly smaller is OK. Finish with the one of the actual washers from the syringe. Push on one of the leather blanks, smooth side first, then put on another washer. This can be slightly bigger than the other washers, but less than the internal diameter of the barrel. Screw on the other nut and do up tightly.

Place the assemble in warm water, and leave for a ½ an hour for the leather to soften.

Note that if you don’t use the additional washers the leather may crimp around the edges, which will affect the seal. Avoid crimping as this will affect the performance and allow liquid to flow around the washer.

Stage 3

Hold the plunger rod firmly in a vice. Form the leather around the washers roughly into a cup, then push on the sprayer barrel. Do not do up the barrel end and leave off the spray head if you can which will help it to dry. Once dry you can carefully remove the washers apart from the original one and will have a cup washer which is a perfect fit. Repeat the process to get a second washer.

One problem you will have with small barrel sizes is fitting the nut without splaying out the cup washer so much that it is difficult to fit it into the barrel. Try putting a nylon tie or hose clip around the cup washers to hold it in shape while doing up the nut.

Additional Notes

If you have a second sprayer of the same internal diameter you can use this to make two washers at the same time. Take care not to damage the end of the barrel when forcing the washer into it. If the nozzle of the sprayer can be unscrewed you can use that end as the mould as it may be stronger. Or if you have a sprayer which has a collar on the end of the barrel use this. Don’t try this method on barrels which have an internal thread for the plunger cap. If the barrel will not force over the leather then the leather may be too thick. If it goes too easily then you may require a thicker leather or possibly larger washers. If the dry washer fits very loosely in the barrel then the leather is too thin and not compressed enough. If it remains a very tight fit then the leather is probably too thick .

Don’t worry if the washers are a bit distorted as they will still work. If you want to have a go at making special tools to do the job then try spiritburner For information on ready made washers see the links page.