Painting, decorating and home improvement tips blog

Tips on using decorator’s caulk

Posted by Adrian
January 5th, 2009

This is our first tip of the year and may be of use to you if you are planning on having new windows or doors fitted in the coming months. You certainly notice drafty old windows and doors in the depths of the British weather!!
So, onto the tip….
Mastic gun

Tips on using decorator’s caulk
Decorator’s caulk is a flexible filler that can be used to go around windows, doors, ceiling and coving line and along the top of skirting boards. It isn’t any good for filling holes in walls etc, as it cannot be rubbed down like powder filler.

To get the best results from using decorators caulk run it along the crack, not too much (you can always go over it again), once you have a line of caulk use a wet finger to run along the line of caulk to smooth it over.

Once the caulk has dried it can be painted over. If you find once you have painted the caulk with emulsion it cracks, you can go over the caulk with an oil-based undercoat, let it dry, then re-emulsion the caulk.

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Posted in Decorating Tips | 19 Comments »

19 Responses to “Tips on using decorator’s caulk”

  1. James Says:

    My top tip is.. the faster you move with the gun the better.

    A decorator once told me it is like drawing a line with a pencil if you do it fast it normally turns out straight and if you do it slow its all over the place.

    Date posted : March 16th, 2010 at 8:47 pm
  2. Angelo Says:

    It will be easier if you manage to apply the caulk fast but you still have to smooth it with a wet finger.That’s for sure.

    Date posted : May 2nd, 2010 at 12:14 pm
  3. Andy Says:

    It seems that standard vinyl matt and contractor matt are the culprits for cracking. Not getting problems with acrylic matt at all.

    Date posted : May 8th, 2011 at 5:31 pm
  4. graham jones Says:

    i am a decorater and have had lots of problems with all corks that i have used most vinyl paints and contract matt seem to seperate on the cork more often than not and its not because i havent let it dry properly because i have, i know you can undercoat the cork but then you need to let it dry and go over it 3 times which is time consuming. i never used to get this problem but has been happining for about year and half i think something has changed in the formulation not sure im gonna investegate

    Date posted : November 11th, 2011 at 6:56 pm
  5. PaintyCait Says:

    I find nearly all acrylics and emulsions will crack/craze over caulk with only one coat, but after the second coat this goes. I normally run a brush with thinned paint or primer over the areas that require caulking early in the day to seal if it requires it – like on lining paper where you wouldn’t put the caulk directly onto raw paper – then caulk and apply the 2 coats after that, as opposed to coating, caulking and coating again.
    I also find that I can’t use my finger if I have a whole kitchen cabinetry of ahead of me my finger would be GONE (or needing kissed better at the very least), For large projects we cut a chunk of Spontex sponge and use that…but be very careful not to have the sponge too wet. No kissing required

    Date posted : December 9th, 2011 at 9:03 pm
  6. Michael Says:

    I have skimmed my ceiling and now there’s hairline cracks appearing every where can somebody tell me I can get rid of the cracks please.

    Date posted : January 12th, 2013 at 3:19 pm
  7. Adrian Says:

    I assume you skimmed the ceiling with plaster? What was the reason for skimming it? If there were already cracks in the ceiling did you tape them?

    To rectify this problem you can either fill the cracks with powder filler and hope they don’t come back or paper the ceiling with lining paper for a smooth finish or Anaglypta paper for a textured finish.

    Date posted : January 13th, 2013 at 9:03 am
  8. Steve Says:

    @Michael. I had hairline cracks in bedroom ceiling and used polycell crack free ceiling matt emulsion. I was very sceptical it would work but it really did! Been fine for a year now. Got it from b&q.

    Date posted : January 17th, 2013 at 11:19 pm
  9. Kalli Says:

    Wondering if anyone can help I’m a student studying painting and decorating, a question has come up asking how long caulk should be left till you can paint over it, does anyone have a rough idea?
    Thank you

    Date posted : November 22nd, 2013 at 5:25 pm
  10. Adrian Says:


    It says on the tubes but typically it is between 1-2 hours depending on temperature and thickness of caulk used.

    Date posted : November 23rd, 2013 at 7:35 am
  11. Phil Says:

    My plumber has just fitted a heated towel rail to the wall in the bathroom. To get the old radiator off he had to extract the old 12″ metal brackets from behind a wooden panel between the wall and panel. This left a 2 x12″ slots in the panel which he filled with caulk. There is still a dent showing which is noticeable. Do i apply more caulk before painting or can i use wood filler on top of the caulk?

    Date posted : November 6th, 2014 at 10:50 am
  12. Adrian Says:


    Caulk is only meant for small gaps, between 3-5mm deep. Filling it with some would then filling over the top would have been the best option but as the caulk has already been applied I would use either a wood filler of all purpose filler to fill the remaining gap. The rub down smooth and level before painting.

    Date posted : November 11th, 2014 at 12:24 pm
  13. Ashley Says:

    Just had coving put up and there are a few gaps where wall or ceiling isn’t level. Am I best to chalk before or after painting the room?

    Date posted : January 9th, 2015 at 9:03 pm
  14. Adrian Says:


    Chalk before painting room.

    Date posted : January 12th, 2015 at 2:56 pm
  15. Susie Says:

    We have used calk to fill some holes left where we removed a radiator. We have always used calk to fill holes but this time we have greasey marks. We noticed it after putting a couple of coats of Dulux Matt on the wall so rubbed it all down, applied a thick Polycell base coat over whole area and then put two more coats of Dulux on it. It seemed to be fine but this evening we have been in the room laying the floor and we noticed as we finished the floor that ‘grease’ marks’ were showing again wherever we used calk in the past. What do you advise we do now please????????????? All our hard work is being affected by this. Is it because we have used a matt emulsion where in the past we used silk????

    Date posted : February 10th, 2015 at 10:32 pm
  16. Adrian Says:


    Firstly I never use caulk to fill holes as it isn’t designed to be rubbed down smooth.

    have you tried an oil based product over the greasy marks, this may hold it back, apply and leave to dry before going over it with emulsion. It will take a while to dry as it is on an oil based product.

    You say you use silk emulsion before, this has more vinyl in it so can hold marks back sometimes.

    Useful links:

    How to fill holes and cracks
    Decorating and preparation
    Tips on using decorator’s caulk

    Date posted : February 13th, 2015 at 3:19 pm
  17. Steve Says:

    I used chalk to fill in the gaps in between the skirting and the walls,but now after about 3 weeks,of applying ,it looks as if the chalk is separating from the wood and causing more gaps.Is there a way of rectifying this problem ?

    Date posted : February 22nd, 2015 at 5:38 pm
  18. Adrian Says:


    Was this new skirting board? If so the wood may of dried out, simply re-apply caulk.
    The only other thing I can think of is if the gap was wide and caulk has shrunk when dried, again if this is the case simply re-apply caulk.

    Date posted : February 28th, 2015 at 3:40 pm


  1. gap between window and window sill - any suggestions as to how to repair?

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