Spraying MRMDF

[PeteG]

Hello could I please have some advice on spraying MDF? I've ordered an Earlex HV5500 HVLP, and the first of many jobs will be to spray a couple of these small stands.
I was going to mix some PVA with water to seal the MDF first, then sand and start spraying. Any tips from preparing the MDF to using an Earlex would be greatly apreciated

 

[Claymore]

you can buy MDF sealer at DIY shops

 

[PeteG]

Thank you Claymor Has anyone had any experience with HMG Paints? There's a branch not far from me, 5 litres of sealer is £34 Ex Vat, and a 5 litre tin of thinners is £25.00 Ex Vat. Not cheap this finishing business is it Still need a top coat after that!

 

[RobinBHM]

Im not sure sealing with pva first is wise, I would be concerned about adhesion of the primer coat.

I would sand the mdf edges to a fine finish like 320 grit. You may try a light dust coat first to seal the mdf then a heavier coat of primer. However I would say, I use waterbased finished, so maybe you wont need to do that with solvent based finishes.

If you havent done much spraying before, I would make sure you have plenty of board off cuts to do some sprayouts first.

Mixing cups are very useful to have, I use the 600ml clear plastic ones. I havent used the earlex, but generally most paints will need thinning for a smooth orange peel free finish and a mixing cup makes it easy to repeat paint viscosity.

Paint finishes are expensive, sometimes the paint costs more than the mdf in a project.

 

[mailee]

One of the best sealers for MDF is Zinnser bin. It is shellac based and white in colour. Brush on leave for about an hour and then sand. It sands down very easily and can be over coated with anything. it is not cheap costing around £15 per litre but one coat is enough. I use this for all of my MDF jobs now and then top coat with Morrells 2K. HTH. :wink:

 

[Chrispy]

I've used HMG paints and their MDF primer is very good, iI only stopped using it because it was getting expensive compared to others.

 

[PeteG]

Im not sure sealing with pva first is wise, I would be concerned about adhesion of the primer coat.

I would sand the mdf edges to a fine finish like 320 grit. You may try a light dust coat first to seal the mdf then a heavier coat of primer. However I would say, I use waterbased finished, so maybe you wont need to do that with solvent based finishes.

If you havent done much spraying before, I would make sure you have plenty of board off cuts to do some sprayouts first.

Mixing cups are very useful to have, I use the 600ml clear plastic ones. I havent used the earlex, but generally most paints will need thinning for a smooth orange peel free finish and a mixing cup makes it easy to repeat paint viscosity.

Paint finishes are expensive, sometimes the paint costs more than the mdf in a project.

Hello Robin. I tried spraying once last year and sold the compressor soon after. I forgot about mixing cups, will put them on my list along with some finer grit sandpaper, the finest I have at the moment is around 180/200!

One of the best sealers for MDF is Zinnser bin. It is shellac based and white in colour. Brush on leave for about an hour and then sand. It sands down very easily and can be over coated with anything. it is not cheap costing around £15 per litre but one coat is enough. I use this for all of my MDF jobs now and then top coat with Morrells 2K. HTH. :wink:

Hello Allan. Is it either one of these?
http://www.screwfix.com/p/zinsser-bulls ... 1ltr/10135
http://www.diy.com/rooms/zinsser-bin-wh ... 13192809:s

Sorry I have to ask, but what is Morrells 2K? :wink:

 

[mahomo59]

I use the Earlex, and have had great results. Will be using this week for clear lacquer and a pigment lacquer, I've had a Farrow & Ball colour mixed for me Elephants Breath all from Morrells who's head office I believe to be in Manchester? I made a decision a while ago to only use this type of product as I get the best results with morrells waterborne lacquer. Have to wait for a few days to be ordered, but worth it. Collected today; 1 x primer, 1 x colour matched lacquer, 1 x clear lacquer all 5l quantities £108 including the vat.
So far I've not had to thin this stuff. I pour from container to spray gun via a strainer to ensure there is no rubbish going through. Thoroughly clean area where turbine unit will sit as it draws air in from the bottom, currently use a scrap piece of mfc as easier to wipe clean. Clean filter underneath turbine prior to this. Test gun on scrap first. In this weather I'll have workshop nice and warm too. Also speaking to the guy at morrells today, he said warm air flow is important with the WB stuff, I suggested fan heater and he said idea. I go two primer and two top coat.
Hope some of this is any good.

 

[RogerS]

.....
Hello Allan. Is it either one of these?
http://www.screwfix.com/p/zinsser-bulls ... 1ltr/10135
http://www.diy.com/rooms/zinsser-bin-wh ... BQ.prd?....

The second one. Zinsser paints are the DB's. They also produce a free book on painting over awkward surfaces.

 

[RogerM]

Pete - I used an Earlex 5000 to spray my steamed beech and mrmdf kitchen cabinet doors and was well pleased with the result. I used Johnstones water based paint mixed to a Farrow and Ball colour, and used Johnstones own brand primer. 3 coats of primer and 3 of colour. You'll get a "viscosity cup" with the unit and you'll need to play around with the mix by trial and error. I found that 45 secs gave the best results, which in practice meant thinning with 25% water. Strain the mix through one of your wife's old stockings/pop socks to get any lumps out. Failure to do that will clog the gun in no time. Thoroughly clean the unit after use, initially by spraying clean water through it, and then by dismantling and using the brushes provided.

Have fun. It's not difficult or rocket science!

 

[PeteG]

Thank you for the help and advice gentlemen, really appreciated. I hadn't realised how expensive this would be before I ordered the Earlex, and I'm praying I'll be able to achieve better results compared to using a brush or roller! I'm not far from a Johnstone's Trade Centre which is handy, but their prices seem equal to Morrells.
Screwfix stock Leyland Acrylic Primer Undercoat http://www.screwfix.com/p/leyland-trade ... 5ltr/64719 £12.49 for 2.5 litres, and an acrylic eggshell top coat http://www.screwfix.com/p/leyland-trade ... 5ltr/45956 £21.89 for 2.5 litres. Would these be OK?

 

[mailee]

Personally I would go with Morrells for spraying. the 2K I mentioned is a 2 pack system using a catalyst to cure the paint. I use the solvent based one as I don't like water based for spraying. Roger is correct it is the second one I use, brilliant stuff, saves so much time. :wink:

 

[mahomo59]

Hi Mailee how long does the smell take to go? Is extraction critical and long between coats cheers mate

 

[mailee]

Do you mean the Zinnser bin or the paint? Zinnser only smells while it is wet but dries pretty quickly around 30-40 mins. As for the Morrells 2K it does take a few days for the smell to completely dissapear. (this is the solvent based I should add) Also the solvent based should really be sprayed with an air fed mask but there are filtered masks available for small sessions. HTH. :wink: