Sealing MDF Boards

Hi all. This is my first post so im sorry to any admins if i have posted in the wrong place. Please feel free to give me a kick up the **** and move the post to the correct thread ;-).

Hi all again. Just wanted to say thanks for all the posts in the forums, they have been really helpful to me in the past and answered MOST of my questions - except this one regarding sealing MDF boards.

Ive built (building) a full size 2p pusher machine (6ft tall 2ft wide 3ft deep) from MDF.

I have read lots and lots of posts regarding sealing MDF and it's cut edges and i feel really informed on that level, but what i cant seem to find a clear answer on it regarding the FLAT surface of the boards. I have no idea if it's best practice to seal the FLAT surfaces of the boards aswel as the edges before applying primer to the boards.

As direct from the factory, i can obviously see they have a 'skin' on each side of the boards to stop the stuff falling apart, but, can i apply primer straight to these sides or will these also need to be sealed, the same as the cut edges ive made?

If they do, then there is going to be the added cost of enough sealer to do the entire cabinet, but if thats something im going to have to do, then im happy to take the extra expence and time in prep ect.

Any advice would be greatfully app., and if you wish to post any tryed and tested methods ect then feel free to throw your '2 pence worth' in (see what i did there) ;-)

Oh and just one more thing...why are most 'MDF sealers' (branded as that or not) waterbased and not oil based? MDF = Water = Weetabix...or am i missing something obvious here?

Thanks again fellow Screwfixers

Snow

 

Hi Chippie hi Andy. Thanks for the fast replys!

Chippie that's great, no i was more looking for the surface finish to be 'as is' that will be plenty for me, so that's kinda saved me a job by the sounds of it, apart from the obvs sanding and primer applying which i will be doing anyway. I was just worried about the sides of the board ingesting the primer without having added a coat of sealer to them first. That's great. Thanks for the advice

Andy hi. Ok so i didnt really think of that Andy if im honest. Would you recommend spraying direct onto the edges with the sealer or should i be going around them all with some kind of compound before the sealer?

 

Fantastic Andy thanks for that. I have rubbed most of the cut sides down to almost smooth so there are is no loose fluff or anything so im hoping i can get away without compound ect as there are quite a lot of cut edges. Do you have a particular brand that you would recommend for this type of job? Sorry for all the questions, ive cut MDF lots of times, but never had to paint it before. Thanks in advance

 

Hi Devil's Ad. Thanks for the reply. Yes my friend very similar. The 2p is inserted in the slot, falls through a random set of pins on a back board, then drops onto a pusher step, which in turns pushes the coins into a lower play area then eventualy into the the cash tray below if your a winner ;-) It's the kind of thing your would typicaly find in an ammusment arcade/park ect.

Yes it's for indoors only. It will have to be quite durable, but it's only going into a 'man cave' so wont have kids pulling at it or anything, not like in a real arcade. Brilliant Devil's, thats what i wanted to hear again. I just could not be sure if i should be sealing the sides of the boards the same way i would be sealing the cut edges, so i just wanted to be sure. Ive got some great advice already from all you guys, this has really helped me out. I would like to spray the whole cabinet if im honest but i just dont have the space to spray (i will be painting in a small shed) so spraying will be impossible. Rollers & brushes were the plan from the off. I will be ok for spray sealer though as Andy suggested above as now ive found out that i will only need to seal the cut edges, as you and Chippie have both said that the sides will not need sealing too, just a good coat of primer

Just thought, it would be easyer to just upload a pic so you can get the idea of the machine. Thanks again for all the help!

 

Ahhh damn yes i know the one now! Damn we used to play that on the long tables at school! Wow taking me back now haha. Sorry for the misunderstanding but i do know what you mean now. Ahh cheers DA it's my first 'big' project. Ive built small things before, but never on this scale. Best thing is, it's not even for me haha. It's for a friends birthday. They are obsessed with these machines haha so should be a nice prezzie when its finished (better than socks anyway) ;-)

 

Sorry did not respond to the above. Ahh ok i see DA about not using sealer, just the primer. I plan on doing some test pieces with some scrap before the cabinet itself so i'll see how i feel i guess with all the options available. Can i just ask about water based please? Ive seen people say ''no water-based - esp on the first coat'' but leaves me wondering why the hell would they make such a product as 'MDF sealer - water based' if it's so bad for it as others have stated (puzzled look). Seems backwards to me, but if i knew the answer i would'nt be here asking ;-)

 

DA your the man! Thanks soooo much! Really informative read there. Thanks for taking the time out of your day for me and the pusher ;-)

Right i see now about WB. Such small content it make no or very little difference. Thats what i kind of thought, good to have it confirmed.

Yea ive worked with wood before, esp building, but what ive gained there, has been lost to me on the paint process tbh. Ive always passed that job onto someone better qualified. This time its me on my own haha. Really good pointers there for me to take ahead. Exactly my thought regarding the spraying of the machine. I do not have the space or the pro equipment needed for spray and dont fancy killing myself in the process.

Take the point about waiting for it to fully dry, thanks. Also i planned on using satins or a semi-gloss as i dont want the finish to shiny anyway so thats great.

As for the mechanisms, yes my own design and build. By no means unique, im using a 12v wiper motor from a car as the motor which is connected via a set of rods to the pusher step, which runs on a set of draw runners. Think steam train wheels. Rotational motion from the wiper motor to linear motion at the step to push it forwards and backwards. It's working great ;-) As for the rest of the machine, that's the only mechanical moving part tbh. The rest is electrical. Lights, sounds, LEDs ect ect. It all runs off a standard pc power suppy that i have converted into a neat compact unit to run 12v, 5v & 3.5v rails. The whole mech and power probs cost £15 to make as i got a second hand motor off flea bay and the power supply was free from one of my old pc towers. Happy days

 

Ha ha it has gone a little off topic yes lol i'll have the admins after me lol...i say it's all relevant anyway... its the 'finer details' of the project. That's what i'll tell them if you wanna do the same lol. Yes sorry your right reciprocating motion yes thats it exactly.

No but seriously, thanks to you Devil and the other contributors you guys have really helped me out. Weather here at the moment is dire...so the project is on hold at the mo until it improves some what, so as soon as i make some progress, i'll let you know how i go on with the painting. I will be posting a blog of the full build when it's done on another site - start to finish with all the pics - so i'll post a link in the future if you want to see the full build. Thanks again DA and everyone