Can intumescent strips be painted over?
Intumescent seal manufacturers do not recommend the painting over of intumescent strips (seals) but there is not enough evidence to show that the painting of intumescent strips has any detrimental effect on their performance.
It is in fact known that some benefits can be acheived in painting the strips as they are much more likely to react against normal atmospheric moisture.
Generally, there has to be a limit to how much paint should be applied, a common sense approach is not the most scientific but it should be obvious that if heavy painting is applied there is a risk of the seals being rendered inoperative, the "brush" strip section should never be painted, it is accepted that a maximum of 4 or 5 coats of conventional oil bound paint or varnish is used.
Be aware when preparing a frame for redecoration, the use of heat or chemical strippers must not be used if intumescent strips are fitted.
For further clarification contact the seal manufacturer for supporting evidence and advice.