"Furry" edges in MDF

[keith]

Hi All,

I have been running into this same issue for years. I do a lot of indoor sign work. I use MDF because it is cheap. I paint, mask, cut, paint, and I'm done...(usually!)

The MDF that I used to get was great. I bought it at Lowes...it was light colored but it cut great. I always got real clean cuts. In the past few years however I've noticed a change in the quality of the MDF I purchased. I tried buying from other supplies but unfortunately I get the same result. I get what I call "furry" edges on my signs. In some cases it looks good, but in most it looks bad. I can sand it but it doesn't always come out as I had hope for. I've included a picture for your thoughts.

Is it the material? If so, do you suggest alternatives? I need cheap, (of course!) machinable, paintable, sheet-type of material.

Could it be my speeds and feeds? If so, what do you suggest?

Dull cutters? It is possible, but I believe I remember seeing this with new cutters as well.

Thanks again!

-Keith

[knight_toolworks]

when you say say other suppliers do you mean box stores? I know the mdf I get from my wood store is better and costs less then the home depot stuff. it has a smoother face and cuts without fuzz.
so try a higher end supplier it may save you money.

[srwtlc]

There is single and double grind MDF (so I was told from my supplier). Double grind is finer and therefore cuts cleaner and finishes better.

[Gary Campbell]

Keith...
Assuming you are not cutting in climb direction, I am with Scott and Steve. Buy better (more expensive pro grade) MDF (60%) and do a test with a designed for MDF bit. (40%)

[knight_toolworks]

the sad part is it costs me less for the good stuff then it does for the borg ****. with a harder smoother face it may save you painting time too.

[bob_s]

Try coating the edge with a mix of 40% water and 60% titebond type II.
It will take abot two hours to dry then sand with a 320 paper. I was amazed.
I do use the better quality mdf and I am spraying ML Campbell water based lacquers, maybe your results may be different. I apply the glue mix with a pad, the kind that has a nap over a sponge attached to a cheap styrofoam handle from the big home centers. If you do surface carving then you have to coat the entire surface to get a good finish, but it takes so little time I just do it all that way. The pad cleans up in less then a minute and I mix the solution in a kitchen soap bottle with the pull up top so there is no waste, just shake it it a minute or two before you pour some on the pad.

[adrianm]

99% of what I do is MDF these days. I switched to the green coloured moisture resistant variety when the quality of the normal stuff started going downhill in the UK.

I find it much better to work with and the small extra cost is more than recouped by the reduction in labour finishing it.

Of course things may well be very different that side of the pond!

[knight_toolworks]

the sad part is it costs me less for the good stuff then it does for the borg ****. with a harder smoother face it may save you painting time too.

[Big-Tex]

We must learn to use cheaply made products as an American industry is competing with more and more "imported" (Chinese) sheet goods.
I see this first hand every day in millwork manufacturing. Prices for jobs under cut, wages under cut and imported materials over taking market. We can not stop corporate "ingenuity" to force more profit, get better yields and find inovative ways to improve so called lean manufacturing.

What big business is doing to all of us is leaning middle class and leaning an American industry and economy. Yes I am sick and tried of it and I am voicing my opinion. We as people of this great land should do it more maybe we the people will be heard.

Sorry to get of the initial subject.

Yes there are still good grades of MDF you just need to ask various vendors for better density of material. Just to give you an example. High density particle board is hard to get in southern region due to architects not specing it and manufacturers take advantage of it and buy cheap particle board. In north eastern areas it is still produced and specifications call for it.
Just do your homework call in various suppliers.

[dvmike]

I did some Extira signs lately and have experienced the hairy cuts as well.
I found a pretty easy fix for it on Extira. I use a small propane torch to run over the face of the sign. It will singe the hairs off easily.
Give it a try on MDF. Just move the torch fairly quickly because it will burn .

[joe]

We shouldn't complain!

Never before has there such abundance of materials and supplies available to us. Lumber from all around the world is available for our asking, not to mention the razor sharp tools setting at the supply house made just for us. Cheap too!

So ever now and again we have a little lumber fuzz or some boards a little too damp, so what. We can move on down the row to something else.

Sometimes I'm guilty of poor thinking which is the "Fuzz" that holds me back. We have a great future in this country and there is plenty of good work for the creative mind. Wish I were younger so I could buy more equipment and make longer ranged plans.

Joe

[GlenP]

Hey guys. Hope all is well. I have seen some changes in mdf quality here in Ontario Canada as well even at my wholesaler level. When you work with mdf you have to expect alot of sanding to get excellent results. I do allot om mdf doors and I have have found works for me is to sand with 120 grit to start and then 280 and then use 400 in the cut open edges. The 400 with almost give some glossy effect to the edges but that is what you want as it is then closing up the cells in the mdf. I usually use lacquer on my doors and spray what I call a sealer coat on first which is 50 % lacquer and 50 % thinner. Sand with 400 after sealer and then I am ready for top coat. I makes a great finish. If you are painting these signs with paint try oil base primers for your primer (sealer) coat and then sand. I personally find oil base primers work better on mdf and especially extira. Always always always sand all areas of your work before doing finish work. I have seen people on sand edges and cut spots figuring the mdf is fine on the flat spots but you have to sand to make a good bond for the paint. I my opinion sanding is the biggest part of working with mdf whether you use the cheaper "shop grade" material from Lowes or the higher grade found at wholesalers. Not get sanding and show us the results. I will try and find the ML Campbell tips and trick sheet for mdf. Very helpful.
Take care all.:)

[woodworx]

What you want to use is a domestic board. Plum Creek SR2, Medite II, or Medite 3D. These boards are super refined particles which gives you a smoother cut. Extira does not have super refined properties, but I can see where the torch idea might work.

Lowes or Home Depot buys regular Medite I or any other cheap MDF they can get their hands on. Ask your supplier to have their mill rep give you a call and explain the properties of the panel you are buying, and the results you are trying to achieve. I guarantee you will get better information from the mill rep than your lumber salesman.

MDF raw materials can even vary from spring to fall. Your color and density will change as the particles that make up the board are harvested at different times of the year.

Higher volume purchases....Maybe even 10 sheets or more will allow you to buy a much better product for 20-30% cheaper than the big box stores.

Justin

[joe]

Justin,

Please tell me more about the latest version of Medix. I'm hesitant to use it again because I lost so much money using it for signs in the past. That was because the top surface was water "Resistant" and the interior wasn't. It would puff up around screws and nails. We had to replace several ground signs. I think you can understand why many of us are leary.

What's the difference between the version #2 & #3?

With Extira, I tested it by cutting of a few pieces and soaking them for a few days in water. That's now my regular test for new materials. Wonder how Medix will do?

Joe Crumley
www.normansignco.com (http://www.normansignco.com)

Perhaps I should get a sheet or two and conduct a test or two. Is there another sign soul doing any kind of testing on these products?

[woodworx]

Anyone who has done the dunking test will know Extira holds up much better. Sierra pine won't put the money into creating a new product that really competes on a moisture resistance level. Machining is a different story. The binder, treatment, and composition blend of these panels are quite different so you can expect different results, but then again there is no perfect mdf on the market.

Medite II and 3D are higher density mdf panels. The harder it is, the nicer it machines, and that is true with any product that your are machining. Plum Creek and the higher density MDF's on the market are good for face milling, and provide great edge quality.

If you look at the sides on a particle board or mdf panel you will notice the core is much denser as it gets closer to the faces. The center of the core is much more porous. When they squish the 12" of fluffy sawdust down to make a 3/4" mdf sheet the load compression is much higher on the face and back of the panel.

When you are working with a finer particle you can ensure that core will be the same density all the way through the core, therefore providing consistent machining.

Justin