Airless spray tip blocking is annoying and can ruin the spray painted surface with spatter or heavy lines of paint. There are a few common reasons causing airless spray tips to block and one of the most common is a problem with filtration of the paint within the airless spray equipment.
Most airless spray guns utilise a filter in the handle of the spray gun which should be fine enough to remove any particles that are large enough to block the airless spray tip that is being used. Check the filtration guides from the airless spray tip manufacturer to ensure you are using an airless spray gun filter in the correct range. If the filter is within the correct range check the filter carefully for any openings in the mesh that may be allowing larger particles to pass through the filter and block your airless spray tip. Filters in many airless spray guns utilise a spring to keep the filter located in the head of the airless spray gun. If this filter is missing from your airless spray gun and the spray gun filter does not screw into the head of the airless spray gun the flow of paint through the airless spray gun may be bypassing the spray gun filter entirely causing blocking of your airless spray tip.
Airless spray tips with wider fan patterns have openings that are much narrower than an airless spray tip with a narrower fan pattern angle. This causes wider fan angle spray tips to be more susceptible to blocking than narrower fan angle airless spray tips. Occasionally simply reducing the fan angle will also reduce the incidence of airless spray tip blocking.
If the filtration used is correct, and within the range recommended by the airless tip manufacturer for the airless spray tip size used, then possibly a larger orifice spray tip may be required for the paint being airless sprayed. Try one orifice size larger airless spray tip to see if the incidence of tip blockages reduces with the larger airless tip size.
Keeping a range of airless spray tips and airless spray gun filters on hand will almost always allow airless spray tip blocking problems to be quickly diagnosed and overcome on-the-job.