Cleaning of spots

A tent is subject to all sorts of abuse but forget wind and rain, a question we're often asked is how to shift bird droppings and tree sap. Well, we've got some suggestions.

Bird poo

Bird excreta is a nasty mix of faeces and urine but it’s easily removed by brushing off if dry or gently washing away with a mild ph-neutral soap, or a good tent cleaner, before swilling well with clean water. Renew the tent’s external Durable Water Repellent (DWR) finish if this has been stripped away – unlikely with a ph-neutral soap but avoid detergents.

Above: Birds are lovely to watch around a campsite’s feeding station but can relieve themselves of that heavy meal on a most inopportune place – your tent! 


This is often mistaken for tree sap but is, in fact, the sweet sticky secretion of certain insects, like aphids. It creates the splattering effect of tacky dirty rain that looks a disaster. But you’ll find it easily washes off – even heavy rain can often clean it away.

Tree sap

Tree sap often comes as that awful conifer resin that smells delightful yet spreads mayhem like napalm − a sticky mess when heated even by the sun. If left to deal with at home the chances are, unless liberally sprinkled with talc, it will spread and adhere to anything it touches. Remember, it gets stickier and more liquid the warmer it is – and think how hot your car can get.

Official advice

Our official advice is to spot clean using our own Clean Guard before reproofing with Outwell Water Guard. But many Outwell campers have asked if there are other ways to deal with the problem using everyday items that are readily available on the campsite. So we asked for ideas on how to shift resin and then tested a few out to see what worked for us.

First, let’s be clear. The following tests are not sanctioned by Outwell or represent an official line. Why? We already provide the above advice to deal with this problem and it is proven not to damage the tent fabric. OK, chances are you’ll need to spot reproof the tent where the DWR finish is damaged but it will not affect the underlying PU-coating – unlike some of the ‘solutions’ tried here.

When approached only Storm out of the UK’s three big waterproofing specialists could readily provide the knowledge and tools to remove resin – on both cotton and synthetics. Its fabric cleaners are created not to affect a DWR finish and, if reproofing is required, it has a good portfolio of easily applied stain-free waterproofing treatments.

In the workshop

An old synthetic tent provided swatches that were then contaminated with larch resin. I attempted to clean this off while noting ease of use, effectiveness, residual staining, DWR removal and, importantly, damage to the underlying PU-coating. I was unable to test polycotton or cotton.

Removing resin

Ways suggested to remove resin fell into three categories:

  1. Physical − scraping just spread the problem while any attempt to freeze it in order to peel away proved fruitless. Dusting with talc helped prevent stickiness and helped rub off some resin but left residue that had found its way between fibres. Mild abrasives, like bicarbonate of soda, took an age to show any limited success and could potentially damage the fibres.
  2. Dissolve – not recommended for solvents often damage the PU-coating and detergents will remove the DWR finish. Cleaners based on natural products, like citrus, proved ineffective. While most solvents dissolved the resin they also spread it around the fabric where it remained once they evaporated − even after washing with soapy water.
  3. Oil − not only appears to lift resin from the fibres but it also negates stickiness. All oil-based products tried removed the resin when worked in using a cotton bud – some better than others. Any residual staining could often be removed with soapy water and a good swill. In all instances the DWR coating had to be renewed.
    My top three oily products proved to be smooth peanut butter, mayonnaise (full fat, what else?) and WD40 – although this left a stain.

My conclusions? Forget the old wives’ tales and pack a good tent cleaner unless you’ve peanut butter to hand and not fussed about potential damage and staining.

These results do not represent official advice but do show how easy it is to even slightly damage the tent’s finish. In fact, chemical variations between brands may cause even more problems than those tested here. To stay safe use a proprietary tent cleaner.

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