How to apply Zinsser BIN to MDF

[wonderwire]

I am trying to make some furniture using MDF.

I have been recommended to 1) Sand with 120 grit, 2) prime with Zinsser BIN, 3) Sand with 220 grit, 4) paint with Dulux Trade Satinwood.

I am at the second step, and have just applied my first coat of Zinsser BIN with a gloss roller:



You can see it's quite patchy. Is this expected? Should I try another coat, or just move onto the sand + satinwood finish?

Thanks!!

 

[cjard]

Not quite the same situation as you as I was putting zinsser 123 on a plywood wall before wallpapering but I used a foam roller and the coverage was similar. The zinsser is to form a barrier and colour cover up to stop the mdf brown showing through the final coat. If you're satisfied the coverage is good enough to be a barrier then multiple finish coats will achiebve the same result. Personally I'd roller a bit more zinsser on the darker patches as it'll make it easier to get a consistent final coat without using a lot of it

 

[Gerrydelasel]

I'm interested in this as I will be priming some MDF soon too. However, I was under the impression Zinsser BIN would be overkill for MDF... BIN is for priming 'difficult' surfaces and knots, whereas MDF is perfectly uniform so a cheaper primer would be fine, no?

 

[wonderwire]

I did some experimenting. Zinsser BIN is definitely the standout result. Worth the extra £££ IMHO. Other acrylic primers simply didn't match the finish.

 

[OwainDIYer]

And it's probably reduced in Screwfix on Friday.

 

[chappers]

I did some experimenting. Zinsser BIN is definitely the standout result. Worth the extra £££ IMHO. Other acrylic primers simply didn't match the finish.

Its all in the prep I wouldn't bother with Zinsser on new MDF. I would rub back with 250 grit, prime 250 grit again, undercoat x2 if necessary with 250 grit after each,then topcoat x2 with 400 grit in between if you leave much more than 24 hrs between coats.
In answer to your original question I always undercoat until you get a good solid flat colour whether that be one coat or three

 

[Gerrydelasel]

And it's probably reduced in Screwfix on Friday.

How did you know that was going to happen??

 

[OwainDIYer]

How did you know that was going to happen??

Whistles nonchalantly.

 

[Gerrydelasel]

Seriously tho

 

[DavidSWP]

Zinsser Cover Stain for everything