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Building Tips and technical articles. => Paint and finishing => Topic started by: Perry Rose on February 12, 2020, 12:02:54 PM

Title: DC-540 primer.
Post by: Perry Rose on February 12, 2020, 12:02:54 PM: Have we decided on a replacement for DC-540? If so what is it?
Title: Re: DC-540 primer.
Post by: Avaiojet on February 12, 2020, 03:10:49 PM: Not cheap but great stuff. Keep in mind, I don't use dope over this.

https://www.eastwood.com/sem-high-build-primer-grey-16-oz-aerosol.html?SRCCODE=PLA00020&gclid=EAIaIQobChMI_ori3YLN5wIVzZyzCh0cyACmEAQYBCABEgJIT_D_BwE
Title: Re: DC-540 primer.
Post by: wwwarbird on February 12, 2020, 07:00:42 PM: Quote from: Perry Rose on February 12, 2020, 12:02:54 PM
Have we decided on a replacement for DC-540? If so what is it?

Each time mine runs out I replace it with another can of DC540. :)
Title: Re: DC-540 primer.
Post by: Dennis Toth on February 12, 2020, 08:19:40 PM: Ty is right, butyrate dope is not compatible over acrylic lacquer (see attached chart).

Best, DennisT
Title: Re: DC-540 primer.
Post by: bill bischoff on February 13, 2020, 02:06:48 PM: Elsewhere on Stunt Hangar there was talk of Harbor Freight's spray can primer being a substitute for DC 540. After being thoroughly disgusted with my last can of DC 540, I bought some of the Harbor Freight primer. However, I haven't had good enough weather to use it yet.

I got to use some of it the other day. Seemed just like the good/old DC540 to me.

BB
Title: Re: DC-540 primer.
Post by: Paul Wood on February 13, 2020, 03:06:59 PM: Perry,

I use Dupli-Color high-build gray primer from the auto supply stores. It's lacquer based and I've used it over Minnwax Polycrylic (water based) with good results. Fills the sand paper pretty quickly, so I have better luck wet sanding. I use Windex to keep the sand paper clean. NOTE, I do not use dope, only lacquer or enamel for a top coat.

Paul
Title: Re: DC-540 primer.
Post by: Bootlegger on February 13, 2020, 05:31:32 PM: Perry, I have a few cans if you want to come and get them...
Title: Re: DC-540 primer.
Post by: Al Ferraro on February 15, 2020, 06:18:24 PM: I gave a can to Sparky to test and he loves it. y1
Al
Title: Re: DC-540 primer.
Post by: Dennis Toth on September 03, 2021, 01:58:18 PM: Al/Sparky,
Any update on the Crest primer? Where do you buy it?

From the chart I posted early in the thread it seems that it is a good idea to give any primer (other than based butyrate primer) a coat of Nitrate to seal (Nitrate go under all type of paint we use and over all but butyrate and Aero Gloss) and have a good base for butyrate dope.

Bill,
What is the number and description of the Harbor Freight primer?

Best, DennisT
Title: Re: DC-540 primer.
Post by: bill bischoff on September 04, 2021, 08:29:34 PM: The Harbor Freight primer I used is called "Iron Armor Sandable Primer". It is item #60789
Title: Re: DC-540 primer.
Post by: Dennis Toth on September 13, 2021, 04:52:14 PM: I got the Harbor Freight "Iron Armor Sandable Primer" gray, $5.99 in store. I applied it to a new built S1 Ringmaster fuse. It went on very smooth and dried nice. It also shows flaws easily so they can be filled and smoothed off. I am letting it gas off a few days before filling dings and get it ready for color.

Thanks Bill for the suggestion.

Best, DennisT
Title: Re: DC-540 primer.
Post by: Dennis Toth on September 25, 2022, 12:10:02 PM: Guys,
Any update on using the Iron Armor Sandable Primer from Harbor Freight? Is it OK under dope?

Best, DennisT
Title: Re: DC-540 primer.
Post by: bill bischoff on October 01, 2022, 12:17:49 PM: I've only used it under Klass Kote epoxy paint, but no problems there. Like any air-drying product, there will be shrinkage. If you can wait a week before sanding it, you will be glad you did in a couple of months.
Title: Re: DC-540 primer.
Post by: Jim Hoffman on October 01, 2022, 01:58:31 PM: I’ve used the Harbor Freight Iron Armor Sandable Primer rattle can stuff several times over Randolph butyrate dope. Very successful.

These primers are very heavy. I use it after I’ve essentially completely filled the surface with dope with some zinc stearate added. I sand off 95% of the primer and it only remains in the remaining surface pores. I then use a blocking coat of polar grey dope to obtain a uniform surface tone.
Title: Re: DC-540 primer.
Post by: Dennis Toth on November 06, 2022, 06:04:24 AM: Guys,
If using the HB Armor primer, once the surfaced is filled, what block coat color works for white or light-yellow final color? We used to use silver as both the filler/primer, but it may take several coats of the lighter colors to cover which adds weight. Jim mentioned Polar Grey, what other block coats work?

Best, DennisT