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Help With Classidur Extreme Primer

After sanding down dusting and wiping with a microfibre cloth I set about priming some bedroom cabinets with Classidur Extreme Primer that I had left over from when I painted some panelled doors I made for the bathroom cabinets. I now have the same problem that I had then with blobs forming as I painted. I’m confident that apart from a one small section the could have done with finer sanding the surfaces were smooth enough and dust free. Now I have no experience with water based paints on woodwork but it seems as though the primer was drying on the brush and being flicked off onto the painted surface where it formed the blobs.
Does anyone have any observations on this and hopefully some advice on how to avoid it.
I was using a Proform Picasso 2" brush and a Staalmeester One fitch


Hi are they micro blisters,what did you clean surface with?

I didn’t clean the surface with any anything, I scraped and sanded to remove the original stain and “varnish” to leave the bare wood surface. I then dusted it down and wiped it with a dry micro-fibre cloth and or a tack rag.
I’m fairly certain they are solid blobs not blisters but I will try and dissect them tomorrow before sanding them down ready for some Johnstones’ Trade Oil based eggshell.

I once experienced something similar when priming a section of plaster wall with the classidur. Out the blue for no apparent reason a section bubbled, not unlike your photo. They were air bubbles. I sanded them down and carried on!

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Always clean,inside and out and do that first,you dont wont to sand dirt into wood.The trouble is,people use mr sheen on wood,airfreshners most contain silicone,at least if you surgically clean,
them problems shouldn’t be there.

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Good point about the cleaning first, I think in this case the amount that I have removed in sanding will have removed any silicone which could have been present but I will clean first on the remaining cabinet.
I cut a couple of the blobs with a scalpel, they were solid rather than hollow.
After the primer what looked smooth whilst sanding now shows the grain so it’s filling time before the eggshell coats. At the moment I’m veering towards Brummer stopping that I have but I wondered if Prestonett Ready Mixed Filler that I also have might be ok as it says it can be used on primed wood - any comments?

Good morning I used osmo filler the other day great stuff, you can buy in different colours,as well.

I had a similar issue on an antique staircase. I started out being a complete muppet; I did not go back to bare wood! I had crazy reactions when I started painting, and it drove me insane. I finally started again and sanded back to the original wood.

I was not happy when I returned the following day to see blisters like your photos depict. I made the error of not cleaning the wood because I assumed the previous paint would have kept chemicals at bay; I had done so many without a problem, but this time I was so wrong!

I sanded again using 120 Abranet Ace on a Mirka Deros. I then cleaned off the surface with Tikkurila Maalipesu diluted 1:10, and my problems ended.

I like to use Toupret Wood Filler on a lot of my indoor work. It is so easy to shape and sand and it bonds to almost anything! If I am working on wood which requires a robust filler I use Toupret Extrem’ Wood. It is a two-part filler, and it has no depth issues like others.

I always surgicall clean,surfaces right down to the door hinge.

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