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The glue and water mix is what I have been using for years with good success. The sign I made for my business was routed then sealed both sides with glue mix and painted with good quality latex paint. (From the recommendation here by the way). The glue mix must dry overnight before finishing.
I asked in an earlier post if someone knows the difference between these processes. One that works fine for signage may not work as well for furniture. Both processes may be perfect for their respective end use.
My question is there enough of a difference between the two?
Danny thinks the laquer based sanding sealer soaks into the MDF making it harder and therefore more suitable after finishing for furniture. However more sanding is required. This dries faster and can be finished before the glue type sealer.
The High Build Primer reduces the sanding but must build on the surface of the MDF covering the imperfections. Is the result of the HBP as durable (hard) as the sanding sealer? If not this process may not be as suitable for furniture.
What do you guys think?
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With the glue... do you not get as much of the "hair" standing up? Or do you still get that but it is just easier to sand off with the glue before finishing coats?
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Stan...
All are good methods and seem, of course, to work best in the hands of the well practiced.
We used to use a 24% HiBUild Lacquer sanding sealer from SherWil. It dries very fast, but requires multiple thin coats to do the same job as the 54% solids post catalyzed lacquers we use now. 1 coat unreduced equals 3 of the SW sealer. A side benefit is no blushing in our high humidity. If the solids level is as high in the automotive high build primer and it is catalyzed, then it may have similar properties.
Even tho others have good experiences with them, I have never had good results putting water based products on wood or wood products as they swell them and raise the grain more than solvent based. They are much cheaper tho.
Gary
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John,
Give the glue a try. What happens is the mixture causes the fibers to stick up then they dry that way. The glue gets hard and when you sand it down you get a very smooth surface for painting.
One big tip is to spray the entire surface of your project with the glue mixture and wipe off the excess from the unrouted areas before it dries. What I have noticed from not doing this is minor differences in the appearance of the paint after it has dried. Spraying the whole piece (in my case doors) assures a uniform paint appearance.
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I've painted a lot of MDF cabinet doors over the years and let me tell you they can be a lot of work. I usually use the clawlock as the first and second coat, sanding after each coat. Sanding before the first coat doesn't seem to do much for me other than knock off the sharp edges. Depending on the door style, I find I have to sand each door for 15 minutes to get rid of the fuzzies on the routed parts.
On the last couple of door sets, I've done I tried something different that required mimimal sanding. First I sanded, to knock off the sharp edges, maybe 1 minute per door. First coat was Benjamin Moore Enamal Underbody Oil based primer. I spray the edges a second time. Next paint with an eggshell latex paint. Next glaze with another watered down latex paint off a different colour, applied with a rag. And lastly a coat clear coat of Aquavar. The finished look turned out excellent and with no sanding between coats.
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Ernest is right about sanding first. Any mdf part should be sanded with a sanding pad. Buy the ones that look like scouring pads and are made out of plastic. They work wonders and come in many grits down to 000. With these, you are able sand in the nooks and crannies far better than with sandpaper.
Joe,
The difference between the glues;
Titebond = not water resistant
Titebond II = water resistant after it dries.
Titebond III = water proof (I haven't tried mixing water with this one yet. LOL)
BTW the mixture should be milky not yellow so the ratio may be 70/30 water to glue. Test, test, test.
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I've just tried Danny Ray's method using Sherwin Williams "Promar" E-Z Sanding Lacquer Searler B44FT8. It worked great. I used three coats applied 30 minutes apart, sanding with 300 grit sandpaper between each coat. I also followed his method and first sanded with 150 grit, then 220 grit before applying the first coat.
In the past, I've used the high build primer. The problem that I had with that method is that the primer didn't seem to have good adhesion to the MDF. It didn't peel or flake, but it didn't take a lot of effort to scrape and scar the surface.
I've also used Wes Mason's method of using Tiebound with water. I used it 50/50, which, according to his post this morning is too thick. I had problems with 'gumming' and adhesion. I'll have to try his method again using the proper dilution.
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Mike,
I've never really checked the ratio. I just mix it until I can put it into a detail sprayer. That's usually pretty thin. Like I said, testing is the key. The glue mix should be so thin that it will run like water. I have used all of the other methods and found that they don't work any better than the cheap glue sizing.
I really think that once you get the ratio right, you will be sold on this almost free method.
regards
wes
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One thing everyone seems to be overlooking is the proper preperation of the mdf. You must sand it with a high grit paper prior to sealing . A good 320 grit will close the pores of the mdf so it will limit the soaking up of the finishing materials, Yes its 1 more step but it will cut down on fuzzing and yes you do need to sand between coats. Remember the whole project can be ruined by a bad finish job .
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Mike Richards,
HIGH BUILD PRIMER
"In the past, I've used the high build primer. The problem that I had with that method is that the primer didn't seem to have good adhesion to the MDF. It didn't peel or flake, but it didn't take a lot of effort to scrape and scar the surface."
HBP readily soaks into MDF and will not peal. Since it's a primer, soft and receptive, for good paint adhesion it will show scuff marks. That's good.
Products like this are for proessionals. You'd be well served to leave it alone.
