I need help to learn how to make perfect vernish on our veneered honeycomb panels

[robherc]

The "el-cheapo" foam brushes I was referring to were not a specific brand name. I was using "el-cheapo" to refer to any cheap foam brush that you can pick up at a discount store. The ones I use cost me about $3 for a package of 10 brushes.
As far as technique goes, I dip just the tip of the angled part of the foam 1-2mm into the varnish (I like spar urethane...good all-weather varnish, but it's not especially cheap) then smooth it onto the surface. Each dip covers about 7-15cm of surface, the same width as the brush, depending on how much urethane soaked into the foam. It's a VERY labor-intensive process, but it yields a good, high-gloss finish coat for me.

A HVLP (High-Volume Low-Pressure) sprays more media (varnish) with less air pressure than a "conventional" air spray gun. I'd still highly recommend an airless spray gun for varnish though, as most HVLP and "standard-pressure" air spray-guns require you to thin your paint/varnish, and this won't help smooth your finish coat much...although it WILL make the process require more coats to get to the same build thickness.

Originally Posted by PAR

You can dilute epoxy with xylene, but it dramatically weakens the molecular bonds within the epoxy. Adding solvent to epoxy isn't a good idea, unless you have a very comprehensive understanding of the chemistry involved. If you need to change the viscosity of epoxy, you should work at higher temperatures.

As usual I widely agree with your recommendations, but here is a possible solution to control viscosity by adding a diluent based on epoxypropoxy.
That does not weaken the crosssections too much because it is a ACTIVE diluent. For cabinetry it should be fine anyway, I would not recommend in applications with highly induced stress.
http://www.ezentrumbilder.de/rg/pdf/...ent_EPD_BD.pdf
and:
http://shop.ezentrum.de/4DCGI/ezshop?hid=27&sprachnr=2

best regards
Richard

[PAR]

Richard, I didn't see anything on that site that was a diluent. Can you provide a direct link to the specific product?

Teakcell, most of the chemicals typically used to thin epoxy, will alter the physical properties of the cured epoxy. Most affect the molecular crosslinking that takes place, by working against a complete 3 dimensional link or physically presenting certain percentages of 2 dimensional linkage from occurring. In all cases, this lose of linkage will weaken the epoxy. In defense of this "thinned" epoxy debate, there are times when you may want to change the physical properties of the cured matrix and specific chemical dilution can provide a means toward this. Preforming this with predictable results can be a tedious and drawn out process of testing and re-testing. I personally have a few different mixtures that I use regularly, in application specific roles. They've been repeatedly tested and now have stood the test of a couple of decades in service, so I can predict their performance accurately. None of my special mixtures are used in any finishing applications.

[teakcell]

Can you be more specific with the mixture that you use? You said that ep can be liquid when heat. Which temperature do you advise and which tools do you recommend to apply the ep and pu ?

[teakcell]

Would anyone knows where to find plans or drawing, explanations on how to make a proper painting room? Which air temperature do wee need, air flow in and out ...

[robherc]

Hmmm, just a thought...

Why not simply use a lower-viscosity epoxy? Depending on the finished properties you're looking for, there are some excellent epoxies out there with viscosities that go down to below 500cps...some are even thinner than most varnish. surely any of those would work very well for a surface-coat epoxy to fully saturate your veneer prior to varnishing. Some of them (heat-cured) even have pretty favorable hardness, strength, and heat-deflection properties, good enough for usage in (some) structural laminates.

[teakcell]

Good idea but I have troubles finding more than one supplier here! We have have one type of glue. I can always import and stock but I try to avoid that as I have enough stock.

[robherc]

Originally Posted by teakcell

Would anyone knows where to find plans or drawing, explanations on how to make a proper painting room? Which air temperature do wee need, air flow in and out ...

I'd recommend doing a patent search for "paint spray room" with Google at http://www.google.com/patents . Any patent that's over 7 years old is considered "expired" and can be used by anyone.

Originally Posted by PAR

Richard, I didn't see anything on that site that was a diluent. Can you provide a direct link to the specific product?

.

PAR
unfortunately not possible, but:
http://www.r-g.de/
change language..... left side bottom
goto E-shop.........click......Epoxy resins....click.......EP additives ..aahhh
see them all ... be jealous....... bloody Huns

With pleasure
Richard

[teakcell]

Originally Posted by robherc

I'd recommend doing a patent search for "paint spray room" with Google at http://www.google.com/patents . Any patent that's over 7 years old is considered "expired" and can be used by anyone.

well thought. Thank you

Originally Posted by teakcell

Would anyone knows where to find plans or drawing, explanations on how to make a proper painting room? Which air temperature do wee need, air flow in and out ...

Laurent,
might be worth to ask one of these guys ? PM?

The AWLGRIP Knowledge challenge

Regards
Richard

[Kaptin-Jer]

I don't know the availability where you are, but I have been using paperbacked veneer and I have not had any bleed through. I am not vacuum bagging only rolling with a laminate roller, low tech but it has been working well.

Originally Posted by Kaptin-Jer

I don't know the availability where you are, but I have been using paperbacked veneer and I have not had any bleed through. I am not vacuum bagging only rolling with a laminate roller, low tech but it has been working well.

Kaptain
He is in Burma, almost nothing available there. And his problem might be that he uses Teak (oily), but he must use Teak.

Regards
Richard

[teakcell]

Originally Posted by Kaptin-Jer

I don't know the availability where you are, but I have been using paperbacked veneer and I have not had any bleed through. I am not vacuum bagging only rolling with a laminate roller, low tech but it has been working well.

Yes, good idea too. I don't really have trouble with Ep going through the veneer and I would even say that I like that because it cannot be better bonded. My problem comes after applying another layer of ep and additionnal Pu varnish in order to reach a top mirror quality varnish. I have only one kind of epoxy available in the local market. I can always import but it is a real trouble here. So, as long as I can do with available products, I will try.

[teakcell]

I did. Thanks