Problems with zinsser bin, painting mdf

Hi All,

(my first time ever posting in a forum - very exciting!!!)

I've been painting an mdf cupboard and doors in the house and it's all gone wrong. If anyone could offer advice it would be much appreciated.

We have an mdf cupboard and i painted it with zinsser bin for a sealing coat. the mdf was cleaned, dried and was painted with a clean foam roller. the problem is the finish is terrible. I did one batch of painting one day which was a barely ok - seems flat'ish after a sand.

but the bits i painted the next day are terrible - its way too rippled and textured, even after a good sand its still not smooth. (I painted outside in very hot weather and the paint dried very quickly.)

Obviously seeing it go wrong I didn't stop there but waited a little while and tried to sand it down. Too soon I guess and big chunks of paint came off. At this point my wife 'advised' me to get away from the cupboard...

Would anyone have any advice for what to do next? Should I sand with rougher sandpiper till its flat? Should I sand the patch that came off and just spot paint that with Bin??

Would people recommend what to go on top of the Bin(I'm hoping to get to a nice white finish one day) and also I have another cupboard (untouched mdf) - is Bin still the best thing for me to use their or do you prefer other products? Maybe Bin with a paint conditioner??

Help is greatly appreciated! thanks

BIN is as you know very fast drying! Zinsser bullseye 123 is a little more forgiving both while they dry fast (about an hour to re-coat for 123) they take a time to fully cure, a couple of weeks is not unusual.
In this time the can be scraped off with a finger nail but in time will cure and fully bond to the surface.
You do not need to wait two weeks for top coating just be aware the surface is still easily damaged.

Rollers always leave an orange peel texture some really expert painters will apply with a roller and then lay off with a good quality brush but that takes years of practice.
The only way to get super smooth is to spray but you still need to be good at it.

Painting in this heat and humidity is asking for trouble wait till the cooler weather, just a light sand between coats is all you need as the coats build up they usually look better.
Tree huggers have given us hopeless water based paints that have little or no "open time" almost drying on the brush!
It helps with water based paints to wipe down the surface with a damp lint free cloth directly before painting, you can add things to top coats to slow the drying time not the zinsser though.

https://www.owatroldirect.co.uk/decorating/paint-additive/

that stuff is pretty strong smelling to me, can't imagine what was around before any changes!

i've applied paint to the 'hole' that was sanded too hard. I'll give it a few days and hopefully i'll be able to sand it flat...

thanks a lot for the help

Consider using a kosher MDF primer instead? Just that bit slower drying, rather than meths based paints.
Zinsser is and excellent barrier treatment though, great for covering a coating where the new top coat isn't compatible.
John

if there is a next time that will be the way I go. We did another cupboard like that a year ago and it turned out fine, this time we over-thought things a bit...

BIN only smells because of the alcohol that it uses as a solvent. The smell dissipates once it is touch dry.

For many years my bread and butter was painting MDF bookcases and wardrobes.

I once made the mistake of using BIN as the primer on a 6m long bookcase. Previously I had always used the Leyland acrylic primer but hoped that the BIN would be non-grain raising (thereby reducing sanding times). Well, it was indeed non-grain raising but the brush stokes were so pronounced that I spent 4 days sanding it flat (compared to 1.25 days to sand the Leyland).

Now the only primer I ever use the Leyland Trade acrylic primer/undercoat when hand painting MDF. It is the only waterbased primer that I have found that is a dream to sand. That said, I pretty much sand nearly all of it off. I sand until I can see the parallel lines created when the MDF was machined at the factory. The fact that the Leyland is extremely cheap is an added bonus.

I have previously tried waterbased MDF specific primers. They raised the grain as much as generic waterbased primers and were a pig to sand flat- they clogged my abrasives. Additionally, the way they dried on my brushes ruined my (£15+ each) brushes. I can only imagine that they might be worth the extra premium if you aren't looking for a high quality finish and plan to use waterbased paints over them. I only use oil based topcoats.

Occasionally, my customers want a sprayed finish. I tend to use acid cat or precat primers, they do not raise the grain but they can not be used on site because of the toxic fumes, Again I sand the back to virtually nothing.

Sorry, getting back to your sanding issues. BIN takes about a week to fully cure but it is very hard to sand. Can you borrow a random orbital sander? 180 to 230 grit should flatten the finish.

I did just this. Waited a while and then put a sander on it and it actually came up nicely. Though the other things we have to do we will definitely NOT be using BIN!

thanks for the help

I take it BIN is best for priming IKEA laminate particle board? What is so good about Leyland and what else is it good/not good for?

Sheepdisease said:

I take it BIN is best for priming IKEA laminate particle board? What is so good about Leyland and what else is it good/not good for?

Click to expand...

BIN will be far more scratch resistant than acrylic primer.

The Leyland acrylic primer is my go to primer for MDF, plaster and woodwork, as previously stated, because of the ease of sanding. Other primers, such as the Dulux Trade acrylic primer give far better colour coverage but are a PITA to sand.

When painting woodwork, I don't care about the fact that the Leyland doesn't obliterate the colour of the grain, I leave that up to the oil based Dulux Trade undercoat.

opps said:

BIN will be far more scratch resistant than acrylic primer.

The Leyland acrylic primer is my go to primer for MDF, plaster and woodwork, as previously stated, because of the ease of sanding. Other primers, such as the Dulux Trade acrylic primer give far better colour coverage but are a PITA to sand.

When painting woodwork, I don't care about the fact that the Leyland doesn't obliterate the colour of the grain, I leave that up to the oil based Dulux Trade undercoat.

Click to expand...

How would Leyland compare to BINS on Ikea laminate wardrobes?

The Leyland would not pass the proverbial "fingernail scratch test". Irrespective of what top coats you applied after, there is a high likelihood of the finish chipping.a site

BIN would be better but I'd recommend lightly sanding the surface first with 180 to 240 grit paper.

Last year I was painting cabinets on a site where the decorators were using BIN to undercoat the previously varnished doors. They didn't bother sanding the doors first. Every door had chip marks on the edges by the time that the other trades had finished.

BIN is great product but Zinsser's claim that surfaces don't need sanding prior to painting is marketing BS.

Thanks for your reply. If it doesn't pass the scratch test, what good is it how well Leyland sands if it doesn't protect the surface properly? I'm probably missing something here...

On absorbent surfaces, such as wood and MDF, the Leyland soaks into the substrate and passes the scratch test.

It is not suitable for use on "hard" non-absorbent surfaces.

When painting wood/MDF, I could use oil based primer but it takes much longer to dry and I would have to wait much longer before i can sand it back.

For painting IKEA laminate type stuff, don't use BIN, use 1-2-3 Bullseye. Longer to dry and great results. Surfaces don't need sanding, just a quick wipe over with meths to remove any oils or grease, they paint away.

Thanks for your reply. Everything I have read has said not to use 123 Bullseye because it will chip off?