Mdf finishing

[g_hinton]

I don't usually work with mdf but I am doing some plunge routing and can't seem to get rid of the hairs when finishing. I have tried primer, sanding sealer, shelac and 2 different brand new router bits. What am I doing wrong? All help is greatly appreciated.

[khaos]

I heard someone talking about a torch. Lightly going ofer the hairs with a little propane torch action cleared the hair without singing the work!

HTH,

[harryball]

I find the type of MDF makes a big difference. Trupan cuts clean with few if any hairs. Some of the stuff I get from HD leaves hairs. Using a torch works. I've also found priming with Kilz2 then sanding lightly works well too.

/RB

[sam_harbold]

Look for Premier Plus or Double Refined MDF. A world of difference over the standard MDF when it comes to machining.

[khaos]

FYI: That torch post was in this thread http://www.talkshopbot.com/forum/mes...315/30750.html and regarded pressure treated wood. no idea why it wouldn't work for MDF...

[myxpykalix]

I use bits from www.centuriontools.com and i don't have any hanging hairs. They cut real clean and are good and sharp.

[jseiler]

Torch also mentioned in this thread:

http://www.talkshopbot.com/forum/mes...312/13496.html

Dremil abrasive puffs work pretty well too if you can fit them in. 3m makes abrasive disks (they look little disks with nylon abrasive hairs hanging out of them) that work in for fine detail. I think foredom has them on their site.

John

[br928]

Check out Danny Ray's MDF finishing techniques here.

http://www.talkshopbot.com/forum/mes...9456#POST68351

Gary, try this and let us know if it works for you.

[joe]

We been using a very simple painting technique on all composite wood surfaces. It's called High Build Primer. Like sanding sealer, it's lacquer based. The big difference is it's made as a filler. Not a sealer. No sanding and sanding and sanding.

Any automotive paint store has High Build Primer. It's thick and needs thinning. Two coats and it sands to a slick finish with 400p.

[br928]

Joe,
Do you do an initial sanding prior to the first coat?

Danny feels the sanding sealer soaks in and provides a harder more durable surface. Do you think the high build primer has the same effect?

Since you both are coming from different application backgrounds (signs / furniture), I am wondering if your approach is application specific. i.e. one better for signs, the other better for furniture.

I guess I am lazy and should just try both and see for myself but this forum saves so much time! (Hey, just using my resources right?)