mdf question

[ynot1234]

Can anyone tell me, is it ok to spray automotive primer over bare MDF. i want to use acrylic lacquer as a top coat. Thanks.

[Master Splinter]

Yes, and it works very well.

[ynot1234]

Thanks Mastersplinter. So the thinners does not create any problems with the bare MDF ?

[Master Splinter]

No - in fact after any routing and sanding, I wipe the surface down with automotive thinners or wax and grease remover to help get any loose MDF dust off it.

If I'm using automotive acrylic, I tend to stick with car finish prep all the way - any filling is done with polyester (or much better, epoxy) bog, acrylic primer-surfacer for 'end grain" (or should that be 'end dust'?), and treat it much like a car panel with the exception of not wet sanding till there's a good number of coats built up.

[ynot1234]

Sounds good. What size nozzle do you use on the finish coat? Any advice on spraying the finish coats would be appreciated.

[bsrlee]

Yep, any water based finish can be a problem with regular MDF, at least with automotive lacquer you should also be proof against rings from wet glasses, which looks ugly real quick. Also second the recommendation to use filler on any cut edges before spraying the finish - it may look smooth but the first coat of finish brings out all the defects & problems.

[ynot1234]

Also , sounds like the old type suction guns (star 770 style) are more suited to laquer than HVLP.
Anyone confirm that?

[Master Splinter]

Suction or gravity fed.

I prefer the gravity fed as I can lower the air pressure a bit more with heavier paint (ie primers) and have less chance of dry spraying. VG Autopaints can sell you a cheapie gravity setup with 1.4, 1.8 and 2.5 needles (http://www.ebay.com.au/itm/ws/eBayISAPI.dll?ViewItem&item=251194955743) for $100 odd. Probably won't be the most comfortable gun to hold, but at that price it gets you started).

(no association with them, I just think their instructional videos are good)

ALERT - VEK Tools has the same kit for $79 (http://www.vektools.com.au/workquip-air-tools/workquip-gravity-feed-spray-gun-p-3556.html) - so if you feel inclined, support a sponsor of the Woodwork forums!