A quick guide to testing your drysuit for leaks.
To test a drysuit for leaks;
Turn the suit inside out. If the suit is fitted with an inflation valve unscrew it and reverse fit it so it is pointing inside the suit this enables an air supply to be attached. Close the zip by putting a hand in through the neck seal.
Insert suitably sized cylindrical objects (5cm-8cm in diameter, at least 10cm long) into the wrist seals and secure them in place with PVC electrical insulation tape.
Into the neck seal insert a cylindrical object (12cm-14cm in diameter, at least 15cm long) and secure with tape. Suits with no valves are best inflated by fitting a tool made for the purpose with a connector to match your supply, if a lot of testing of suits of any type is anticipated then this tool makes the job easier.
Connect to the compressed air supply and carefully begin inflating the suit. The correct test pressure when testing in air 0.3 PSI this can be estimated with out a gauge in the following ways. On suits with latex neck seal when its diameter expands to reaches 25cm. Or if it has neoprene seals when the neck seals just start to expand.
Over inflating a suit can damage it.
When the suit is inflated to the correct pressure use a sponge to cover it with soapy water, looking carefully for any bubbles being formed. Mark any leaks with a waterproof pencil.
Keep topping up with compressed air if necessary.
When finished testing remove from compressed air supply, rinse over with fresh water and allow the suit to deflate.
Take great care when removing the electrical tapes so as not to damage the seals.
Hang suit up to dry before attempting any repair. When refitting the inflation valve make sure it is refitted sufficiently tightly.
Still getting wet when diving?
If you can identify where you are getting wet/damp from the state of your undersuit then this can narrow down your search. Bearing in mind that if you are getting a lot of water in when you stand up it will run into your boots, this does not necessarily means that the boots are at fault!
Leaks around the valves are the most common, always make sure that that valves are sufficiently tight and that the correct valve patch is fitted. Make sure that valves are rinsed with fresh water after each dive. Get the valve serviced or replaced if problems persist. By not using adjustable dumps valves full open i.e. putting a quarter turn on it towards the closed position will load the internal spring a reduce a leaks through the vale its self.
Intermittent dampness around the chest on suits fitted with neoprene neck seals can indicate the seal when tucked in has folded or creased in such a ways as to let water creep down, with more care when inverting the seal this should cure the problem. Neoprene necks that are to big or suits that are too short in the body will always leak.
Latex necks are generally very good at keeping the water out, however trying to improve comfort by trimming the neck seal can lead to them being too big, so only trim one ring at a time and then dive. A latex seal is not the most comfortable of things but a leaking suit is worse.
With cuff seals of both types people with very pronounced tendons running down from the wrist can get wet arms from water channelling down under the seal. This can be reduced by pulling the seal away from the worst area either up or down the arms, using gloves with a Velcro wrist strap or a some people have had success with a product called bio seals http://www.apollo-europe.com/bioseals.html . Always check that your undersuit is clear of the sealing area.